This article describes a case of rudimentary meningocele occurring in association with aplasia cutis congenita and focal dermal melanocytosis. Rudimentary meningocele, although considered a form of cutaneous meningioma, is a development anomaly reflecting a form of neural dysraphism. In this regard, other names have been applied to these lesions and likely all are preferred designations over cutaneous meningioma including meningothelial hamartoma, sequestrated meningocele, cutaneous heterotopic meningeal nodules, and acoelic meningeal hamartoma.1-3 Its basis is distinct displacement heterotopia reflective of an embryonic defect in neural tube closure.
Case History
An 8-year-old girl presented with an indeterminate congenital scalp tumor with the clinical impression of nevus sebaceous. Clinical examination revealed a depressed area in the scalp accompanied by localized hair loss. Skull imaging prior to surgery revealed no significant abnormalities. The child was otherwise healthy with no significant past medical history.
With light microscopy, the excision specimen revealed a grossly brown lesion measuring 0.4 × 0.5 cm. Microscopically, there was a complete absence of any adnexal structures accompanied by laminated fibroplasia typical of congenital aplasia cutis (Figure 1). An additional feature was one of dermal melanocytosis defined by a proliferation of slender pigment laden benign dendritic melanocytes within the dermis. In regards to the fibroplasia, the dermis had a hyalinizing quality resulting in expansion of the deeper dermal collagen bundles and interlobular septa within the fat lobule. Within the deeper dermis and subcutaneous fat, monomorphic appearing cuboidal cells with rounded nuclei and a finely dispersed chromatin were noted. The pattern of infiltration was most distinctive whereby this unusual cell population scaffolded along spaces recapitulating a well-differentiated vasoformative lesion. Focally the cells assumed an almost syncytial multinucleated growth pattern in the zones of sinusoidal growth.
However, careful inspection of these spaces suggested that they were pseudovascular sinusoidal-like channels as opposed to representing true vascular channels typical for a vasoformative neoplasm (Figure 2). Foci of psammomatous calcification were also noted. Immunohistochemical stains showed that the cuboidal lining cells were extensively epithelial membrane antigen positive but do not demonstrate any positivity with endothelial cell markers, specifically CD34, CD31, ERG, and factor VIII (Figures 3 and 4). Significant immunoreactivity is not identified for factor-XIIIA, S-100, or Melan-A.
Article continues on page 2
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Discussion
Rudimentary meningocele represents a specific subset of neural dysraphism. Other terms for this rare malformation is atretic meningocele and heterotopic meningothelial nodule. The broad topic of meningeal elements in the skin was first discussed by Lopez and colleagues4 in 1974. In this seminal paper, the authors reviewed 25 cases of cutaneous meningioma. The authors proposed a classification scheme that still holds practical value today, recognizing 3 groups: Type I: primary cutaneous meningioma; Type II: ectopic meningioma of the soft tissue with extension into the skin most commonly arising from the proximal peripheral nerves and found reproducibly in the orbit, face, and sinonasal tract typically occurring in adults; and Type III: central nervous system (CNS) meningioma with extension into the skin.4 Type I occurs on the scalp, face, or paravertebral region at birth; Type II develops around sensory organs of the head along the cranial and spinal nerves; and Type III occurs on the face, temple, and scalp.4,5
Lu and colleagues6 described 5 cases of rudimentary meningoceles that were congenital and presented as alopecic lesions on the occipital area. One could consider a rudimentary meningocele as a form of Type I cutaneous meningioma, representing a displacement of meningothelial cells typically occurring in the parietal occipital scalp region or anywhere along the rachidian axis. In atretic/rudimentary meningoceles there is typically no patent connection with the CNS; there may be a defect in the skull or a fibrous tract contiguous with the intracranial cavity. Kiyohara and colleagues5 described a rudimentary meningocele that presented as “dented” skull defect similar to our case. Other presentations include nodules or plaques on the scalp (temporal, parietal, occipital, paramedian, or lumbosacral). Sibley and Cooper7 discussed 5 primary cutaneous meningiomas with a skull defect deep to one lesion and another lesion that presented as a lumbar polyp that was attached to the dura. Angiomas may be adjacent.1
The morphology of the rudimentary meningocele is most commonly in the context of a lesion that has a histology most reminiscent of giant cell fibroblastoma, the hallmarks being in the context of deep seated irregular spaces lined by epithelial appearing cells typically with a multinucleated syncytial appearance. Calcification or psammoma-like bodies and cyst-like areas may be present. As with this case, additional abnormalities such as congenital aplasia cutis and dermal melanocytosis can be observed. Immunohistochemistry stains that are usually employed during workup include positive stains (EMA, NSE, vimentin, neurofilament) and negative stains (CAM5.2, AE1/AE3, cytokeratin, S-100, CD31, CD34, GFAP, CD57, smooth muscle actin, desmin, CD68). Recently reported is the expression of podoplanin and NKI-C3 and to a lesser extent PR and Glut-11.
Histologically, these lesions should be distinguished from hamartomas with ectopic meningothelial elements as well as giant cell fibroblastomas as they have prognostic differences from rudimentary meningocele. In regards to giant cell fibroblastoma, these neoplasms typically occur in younger patients where they present as slow growing neoplasms that have the potential to recur but not metastasize. They are cytogenetically related to dermatofibrosarcoma protuberans with a similar supernumerary ring chromosome derived from chromosomes 17 and 22. While there is a significant degree of light microscopic similitude between the giant cell fibroblastoma and the rudimentary meningocele, the phenotypic profile certainly allows unequivocal distinction between giant cell fibroblastoma and the rudimentary meningocele. In the hamartoma with ectopic meningothelial elements, patients vary in age at the time of presentation but usually the patients are children and young adults with most lesions occurring on the scalp. One observes a constellation of haphazardly arranged bundles of collagen, adipose tissue, nerves, skeletal muscle, and meningothelial cells. The meningothelial cells assume the same atypical infiltrative vasoformative pattern encountered in rudimentary meningocele, and therefore, simulates giant cell fibroblastoma or in an older individual would suggest an angiosarcoma, especially in cases where the lining cells appear somewhat spindled in appearance.
The patients are typically young children presenting with nodules or areas of induration.3 Aplasia cutis congenita is a frequent finding in the setting of rudimentary meningocele.1 The clinical presentation of a young child with alopecic areas on the scalp, that may be scar-like is the correlate of aplasia cutis congenita.8 There are several studies describing a hair collar sign characterized by a tuft of hair surrounding the skin lesion.1,8 The hair color sign is not specific for rudimentary meningocele and has been observed in other settings including glial heterotopia, membranous aplasia cutis, and encephalocele. Association of meningothelial hamartoma with a nevus sebaceus has been described.9
Regarding pathogenesis, the similar anatomical distribution of the lesion to neural tube fusion sites support the hypothesis that classic meningocele and rudimentary meningoceles are a continuous spectrum representing the sequelae in most cases of abnormal neural tube closure.2 There should be an attempt to discern whether there is a connection from the lesion subdurally prior to biopsy as this scenario defines the classic meningocele which would require neurosurgical intervention. The rudimentary meningocele is currently categorized as a nonneoplastic lesion with attributes of a malformation that is adequately treated by simple excision.3
Dr Magro is the director of dermatopathology at Weill Cornell Medicine in New York, NY.
Henry M. Spinelli, MD is a Clinical professor of surgery at Weill Cornell Medical College.
Mary D. Le, MD is a Dermatopathology fellow, Memorial Sloan Kettering Cancer Center.
Disclosure: The authors report no relevant financial relationships.
References
1. Battistella M, Guedj N, Fallet-Bianco C, Bodemer C, Brousse N, Fraitag S. The histopathological spectrum of cutaneous meningeal heterotopias: clues and pitfalls. Histopathology. 2011;59(3):407-420.
2. El Shabrawi-Caelen L, White WL, Soyer HP, Kim BS, F IJ, McCalmont TH. Rudimentary meningocele: remnant of a neural tube defect? Arch Dermatol. 2001;137(1):45-50.
3. Marrogi AJ, Swanson, PE, Kyriakos M, Wick MR. Rudimentary meningocele of the skin. Clinicopathologic features and differential diagnosis. J Cutan Pathol. 1991;18(3):178-188.
4. Lopez DA, Silvers DN, Helwing EB. Cutaneous meningiomas–a clinicopathologic study. Cancer. 1974;34(3):728-744.
5. Kiyohara T, Kawami K, Kouraba S, Kumakira M, Immamura Y. Dented rudimentary meningocele. J Am Acad Dermatol. 2007;57(6):1101-1102.
6. Lu C, Chan YC, Lai CH, Kuo TT, Hong HS. Rudimentary meningocele of the scalp. Dermatol Sinica. 2003;21(4):394-401.
7. Sibley DA, Cooper PH. Rudimentary meningocele: A variant of ‘primary cutaneous meningioma’. J Cutan Pathol. 1989;16(2):72-80.
8. Kenyon K, Zedek D, Sayed C. Incidental finding of cutaneous meningeal heterotopia in aplasia cutis congenita. J Cutan Pathol. 2016:43(7):609-612.
9. Crittenden SC, Sonnier GB. Meningothelial hamartoma associated with nevus sebaceus. Pediatr Dermatol. 2014;31(2):208-211.
This article describes a case of rudimentary meningocele occurring in association with aplasia cutis congenita and focal dermal melanocytosis. Rudimentary meningocele, although considered a form of cutaneous meningioma, is a development anomaly reflecting a form of neural dysraphism. In this regard, other names have been applied to these lesions and likely all are preferred designations over cutaneous meningioma including meningothelial hamartoma, sequestrated meningocele, cutaneous heterotopic meningeal nodules, and acoelic meningeal hamartoma.1-3 Its basis is distinct displacement heterotopia reflective of an embryonic defect in neural tube closure.
Case History
An 8-year-old girl presented with an indeterminate congenital scalp tumor with the clinical impression of nevus sebaceous. Clinical examination revealed a depressed area in the scalp accompanied by localized hair loss. Skull imaging prior to surgery revealed no significant abnormalities. The child was otherwise healthy with no significant past medical history.
With light microscopy, the excision specimen revealed a grossly brown lesion measuring 0.4 × 0.5 cm. Microscopically, there was a complete absence of any adnexal structures accompanied by laminated fibroplasia typical of congenital aplasia cutis (Figure 1). An additional feature was one of dermal melanocytosis defined by a proliferation of slender pigment laden benign dendritic melanocytes within the dermis. In regards to the fibroplasia, the dermis had a hyalinizing quality resulting in expansion of the deeper dermal collagen bundles and interlobular septa within the fat lobule. Within the deeper dermis and subcutaneous fat, monomorphic appearing cuboidal cells with rounded nuclei and a finely dispersed chromatin were noted. The pattern of infiltration was most distinctive whereby this unusual cell population scaffolded along spaces recapitulating a well-differentiated vasoformative lesion. Focally the cells assumed an almost syncytial multinucleated growth pattern in the zones of sinusoidal growth.
However, careful inspection of these spaces suggested that they were pseudovascular sinusoidal-like channels as opposed to representing true vascular channels typical for a vasoformative neoplasm (Figure 2). Foci of psammomatous calcification were also noted. Immunohistochemical stains showed that the cuboidal lining cells were extensively epithelial membrane antigen positive but do not demonstrate any positivity with endothelial cell markers, specifically CD34, CD31, ERG, and factor VIII (Figures 3 and 4). Significant immunoreactivity is not identified for factor-XIIIA, S-100, or Melan-A.
Discussion
Rudimentary meningocele represents a specific subset of neural dysraphism. Other terms for this rare malformation is atretic meningocele and heterotopic meningothelial nodule. The broad topic of meningeal elements in the skin was first discussed by Lopez and colleagues4 in 1974. In this seminal paper, the authors reviewed 25 cases of cutaneous meningioma. The authors proposed a classification scheme that still holds practical value today, recognizing 3 groups: Type I: primary cutaneous meningioma; Type II: ectopic meningioma of the soft tissue with extension into the skin most commonly arising from the proximal peripheral nerves and found reproducibly in the orbit, face, and sinonasal tract typically occurring in adults; and Type III: central nervous system (CNS) meningioma with extension into the skin.4 Type I occurs on the scalp, face, or paravertebral region at birth; Type II develops around sensory organs of the head along the cranial and spinal nerves; and Type III occurs on the face, temple, and scalp.4,5
Lu and colleagues6 described 5 cases of rudimentary meningoceles that were congenital and presented as alopecic lesions on the occipital area. One could consider a rudimentary meningocele as a form of Type I cutaneous meningioma, representing a displacement of meningothelial cells typically occurring in the parietal occipital scalp region or anywhere along the rachidian axis. In atretic/rudimentary meningoceles there is typically no patent connection with the CNS; there may be a defect in the skull or a fibrous tract contiguous with the intracranial cavity. Kiyohara and colleagues5 described a rudimentary meningocele that presented as “dented” skull defect similar to our case. Other presentations include nodules or plaques on the scalp (temporal, parietal, occipital, paramedian, or lumbosacral). Sibley and Cooper7 discussed 5 primary cutaneous meningiomas with a skull defect deep to one lesion and another lesion that presented as a lumbar polyp that was attached to the dura. Angiomas may be adjacent.1
The morphology of the rudimentary meningocele is most commonly in the context of a lesion that has a histology most reminiscent of giant cell fibroblastoma, the hallmarks being in the context of deep seated irregular spaces lined by epithelial appearing cells typically with a multinucleated syncytial appearance. Calcification or psammoma-like bodies and cyst-like areas may be present. As with this case, additional abnormalities such as congenital aplasia cutis and dermal melanocytosis can be observed. Immunohistochemistry stains that are usually employed during workup include positive stains (EMA, NSE, vimentin, neurofilament) and negative stains (CAM5.2, AE1/AE3, cytokeratin, S-100, CD31, CD34, GFAP, CD57, smooth muscle actin, desmin, CD68). Recently reported is the expression of podoplanin and NKI-C3 and to a lesser extent PR and Glut-11.
Histologically, these lesions should be distinguished from hamartomas with ectopic meningothelial elements as well as giant cell fibroblastomas as they have prognostic differences from rudimentary meningocele. In regards to giant cell fibroblastoma, these neoplasms typically occur in younger patients where they present as slow growing neoplasms that have the potential to recur but not metastasize. They are cytogenetically related to dermatofibrosarcoma protuberans with a similar supernumerary ring chromosome derived from chromosomes 17 and 22. While there is a significant degree of light microscopic similitude between the giant cell fibroblastoma and the rudimentary meningocele, the phenotypic profile certainly allows unequivocal distinction between giant cell fibroblastoma and the rudimentary meningocele. In the hamartoma with ectopic meningothelial elements, patients vary in age at the time of presentation but usually the patients are children and young adults with most lesions occurring on the scalp. One observes a constellation of haphazardly arranged bundles of collagen, adipose tissue, nerves, skeletal muscle, and meningothelial cells. The meningothelial cells assume the same atypical infiltrative vasoformative pattern encountered in rudimentary meningocele, and therefore, simulates giant cell fibroblastoma or in an older individual would suggest an angiosarcoma, especially in cases where the lining cells appear somewhat spindled in appearance.
The patients are typically young children presenting with nodules or areas of induration.3 Aplasia cutis congenita is a frequent finding in the setting of rudimentary meningocele.1 The clinical presentation of a young child with alopecic areas on the scalp, that may be scar-like is the correlate of aplasia cutis congenita.8 There are several studies describing a hair collar sign characterized by a tuft of hair surrounding the skin lesion.1,8 The hair color sign is not specific for rudimentary meningocele and has been observed in other settings including glial heterotopia, membranous aplasia cutis, and encephalocele. Association of meningothelial hamartoma with a nevus sebaceus has been described.9
Regarding pathogenesis, the similar anatomical distribution of the lesion to neural tube fusion sites support the hypothesis that classic meningocele and rudimentary meningoceles are a continuous spectrum representing the sequelae in most cases of abnormal neural tube closure.2 There should be an attempt to discern whether there is a connection from the lesion subdurally prior to biopsy as this scenario defines the classic meningocele which would require neurosurgical intervention. The rudimentary meningocele is currently categorized as a nonneoplastic lesion with attributes of a malformation that is adequately treated by simple excision.3
Dr Magro is the director of dermatopathology at Weill Cornell Medicine in New York, NY.
Henry M. Spinelli, MD is a Clinical professor of surgery at Weill Cornell Medical College.
Mary D. Le, MD is a Dermatopathology fellow, Memorial Sloan Kettering Cancer Center.
Disclosure: The authors report no relevant financial relationships.
References
1. Battistella M, Guedj N, Fallet-Bianco C, Bodemer C, Brousse N, Fraitag S. The histopathological spectrum of cutaneous meningeal heterotopias: clues and pitfalls. Histopathology. 2011;59(3):407-420.
2. El Shabrawi-Caelen L, White WL, Soyer HP, Kim BS, F IJ, McCalmont TH. Rudimentary meningocele: remnant of a neural tube defect? Arch Dermatol. 2001;137(1):45-50.
3. Marrogi AJ, Swanson, PE, Kyriakos M, Wick MR. Rudimentary meningocele of the skin. Clinicopathologic features and differential diagnosis. J Cutan Pathol. 1991;18(3):178-188.
4. Lopez DA, Silvers DN, Helwing EB. Cutaneous meningiomas–a clinicopathologic study. Cancer. 1974;34(3):728-744.
5. Kiyohara T, Kawami K, Kouraba S, Kumakira M, Immamura Y. Dented rudimentary meningocele. J Am Acad Dermatol. 2007;57(6):1101-1102.
6. Lu C, Chan YC, Lai CH, Kuo TT, Hong HS. Rudimentary meningocele of the scalp. Dermatol Sinica. 2003;21(4):394-401.
7. Sibley DA, Cooper PH. Rudimentary meningocele: A variant of ‘primary cutaneous meningioma’. J Cutan Pathol. 1989;16(2):72-80.
8. Kenyon K, Zedek D, Sayed C. Incidental finding of cutaneous meningeal heterotopia in aplasia cutis congenita. J Cutan Pathol. 2016:43(7):609-612.
9. Crittenden SC, Sonnier GB. Meningothelial hamartoma associated with nevus sebaceus. Pediatr Dermatol. 2014;31(2):208-211.
This article describes a case of rudimentary meningocele occurring in association with aplasia cutis congenita and focal dermal melanocytosis. Rudimentary meningocele, although considered a form of cutaneous meningioma, is a development anomaly reflecting a form of neural dysraphism. In this regard, other names have been applied to these lesions and likely all are preferred designations over cutaneous meningioma including meningothelial hamartoma, sequestrated meningocele, cutaneous heterotopic meningeal nodules, and acoelic meningeal hamartoma.1-3 Its basis is distinct displacement heterotopia reflective of an embryonic defect in neural tube closure.
Case History
An 8-year-old girl presented with an indeterminate congenital scalp tumor with the clinical impression of nevus sebaceous. Clinical examination revealed a depressed area in the scalp accompanied by localized hair loss. Skull imaging prior to surgery revealed no significant abnormalities. The child was otherwise healthy with no significant past medical history.
With light microscopy, the excision specimen revealed a grossly brown lesion measuring 0.4 × 0.5 cm. Microscopically, there was a complete absence of any adnexal structures accompanied by laminated fibroplasia typical of congenital aplasia cutis (Figure 1). An additional feature was one of dermal melanocytosis defined by a proliferation of slender pigment laden benign dendritic melanocytes within the dermis. In regards to the fibroplasia, the dermis had a hyalinizing quality resulting in expansion of the deeper dermal collagen bundles and interlobular septa within the fat lobule. Within the deeper dermis and subcutaneous fat, monomorphic appearing cuboidal cells with rounded nuclei and a finely dispersed chromatin were noted. The pattern of infiltration was most distinctive whereby this unusual cell population scaffolded along spaces recapitulating a well-differentiated vasoformative lesion. Focally the cells assumed an almost syncytial multinucleated growth pattern in the zones of sinusoidal growth.
However, careful inspection of these spaces suggested that they were pseudovascular sinusoidal-like channels as opposed to representing true vascular channels typical for a vasoformative neoplasm (Figure 2). Foci of psammomatous calcification were also noted. Immunohistochemical stains showed that the cuboidal lining cells were extensively epithelial membrane antigen positive but do not demonstrate any positivity with endothelial cell markers, specifically CD34, CD31, ERG, and factor VIII (Figures 3 and 4). Significant immunoreactivity is not identified for factor-XIIIA, S-100, or Melan-A.
,
This article describes a case of rudimentary meningocele occurring in association with aplasia cutis congenita and focal dermal melanocytosis. Rudimentary meningocele, although considered a form of cutaneous meningioma, is a development anomaly reflecting a form of neural dysraphism. In this regard, other names have been applied to these lesions and likely all are preferred designations over cutaneous meningioma including meningothelial hamartoma, sequestrated meningocele, cutaneous heterotopic meningeal nodules, and acoelic meningeal hamartoma.1-3 Its basis is distinct displacement heterotopia reflective of an embryonic defect in neural tube closure.
Case History
An 8-year-old girl presented with an indeterminate congenital scalp tumor with the clinical impression of nevus sebaceous. Clinical examination revealed a depressed area in the scalp accompanied by localized hair loss. Skull imaging prior to surgery revealed no significant abnormalities. The child was otherwise healthy with no significant past medical history.
With light microscopy, the excision specimen revealed a grossly brown lesion measuring 0.4 × 0.5 cm. Microscopically, there was a complete absence of any adnexal structures accompanied by laminated fibroplasia typical of congenital aplasia cutis (Figure 1). An additional feature was one of dermal melanocytosis defined by a proliferation of slender pigment laden benign dendritic melanocytes within the dermis. In regards to the fibroplasia, the dermis had a hyalinizing quality resulting in expansion of the deeper dermal collagen bundles and interlobular septa within the fat lobule. Within the deeper dermis and subcutaneous fat, monomorphic appearing cuboidal cells with rounded nuclei and a finely dispersed chromatin were noted. The pattern of infiltration was most distinctive whereby this unusual cell population scaffolded along spaces recapitulating a well-differentiated vasoformative lesion. Focally the cells assumed an almost syncytial multinucleated growth pattern in the zones of sinusoidal growth.
However, careful inspection of these spaces suggested that they were pseudovascular sinusoidal-like channels as opposed to representing true vascular channels typical for a vasoformative neoplasm (Figure 2). Foci of psammomatous calcification were also noted. Immunohistochemical stains showed that the cuboidal lining cells were extensively epithelial membrane antigen positive but do not demonstrate any positivity with endothelial cell markers, specifically CD34, CD31, ERG, and factor VIII (Figures 3 and 4). Significant immunoreactivity is not identified for factor-XIIIA, S-100, or Melan-A.
Article continues on page 2
{{pagebreak}}
Discussion
Rudimentary meningocele represents a specific subset of neural dysraphism. Other terms for this rare malformation is atretic meningocele and heterotopic meningothelial nodule. The broad topic of meningeal elements in the skin was first discussed by Lopez and colleagues4 in 1974. In this seminal paper, the authors reviewed 25 cases of cutaneous meningioma. The authors proposed a classification scheme that still holds practical value today, recognizing 3 groups: Type I: primary cutaneous meningioma; Type II: ectopic meningioma of the soft tissue with extension into the skin most commonly arising from the proximal peripheral nerves and found reproducibly in the orbit, face, and sinonasal tract typically occurring in adults; and Type III: central nervous system (CNS) meningioma with extension into the skin.4 Type I occurs on the scalp, face, or paravertebral region at birth; Type II develops around sensory organs of the head along the cranial and spinal nerves; and Type III occurs on the face, temple, and scalp.4,5
Lu and colleagues6 described 5 cases of rudimentary meningoceles that were congenital and presented as alopecic lesions on the occipital area. One could consider a rudimentary meningocele as a form of Type I cutaneous meningioma, representing a displacement of meningothelial cells typically occurring in the parietal occipital scalp region or anywhere along the rachidian axis. In atretic/rudimentary meningoceles there is typically no patent connection with the CNS; there may be a defect in the skull or a fibrous tract contiguous with the intracranial cavity. Kiyohara and colleagues5 described a rudimentary meningocele that presented as “dented” skull defect similar to our case. Other presentations include nodules or plaques on the scalp (temporal, parietal, occipital, paramedian, or lumbosacral). Sibley and Cooper7 discussed 5 primary cutaneous meningiomas with a skull defect deep to one lesion and another lesion that presented as a lumbar polyp that was attached to the dura. Angiomas may be adjacent.1
The morphology of the rudimentary meningocele is most commonly in the context of a lesion that has a histology most reminiscent of giant cell fibroblastoma, the hallmarks being in the context of deep seated irregular spaces lined by epithelial appearing cells typically with a multinucleated syncytial appearance. Calcification or psammoma-like bodies and cyst-like areas may be present. As with this case, additional abnormalities such as congenital aplasia cutis and dermal melanocytosis can be observed. Immunohistochemistry stains that are usually employed during workup include positive stains (EMA, NSE, vimentin, neurofilament) and negative stains (CAM5.2, AE1/AE3, cytokeratin, S-100, CD31, CD34, GFAP, CD57, smooth muscle actin, desmin, CD68). Recently reported is the expression of podoplanin and NKI-C3 and to a lesser extent PR and Glut-11.
Histologically, these lesions should be distinguished from hamartomas with ectopic meningothelial elements as well as giant cell fibroblastomas as they have prognostic differences from rudimentary meningocele. In regards to giant cell fibroblastoma, these neoplasms typically occur in younger patients where they present as slow growing neoplasms that have the potential to recur but not metastasize. They are cytogenetically related to dermatofibrosarcoma protuberans with a similar supernumerary ring chromosome derived from chromosomes 17 and 22. While there is a significant degree of light microscopic similitude between the giant cell fibroblastoma and the rudimentary meningocele, the phenotypic profile certainly allows unequivocal distinction between giant cell fibroblastoma and the rudimentary meningocele. In the hamartoma with ectopic meningothelial elements, patients vary in age at the time of presentation but usually the patients are children and young adults with most lesions occurring on the scalp. One observes a constellation of haphazardly arranged bundles of collagen, adipose tissue, nerves, skeletal muscle, and meningothelial cells. The meningothelial cells assume the same atypical infiltrative vasoformative pattern encountered in rudimentary meningocele, and therefore, simulates giant cell fibroblastoma or in an older individual would suggest an angiosarcoma, especially in cases where the lining cells appear somewhat spindled in appearance.
The patients are typically young children presenting with nodules or areas of induration.3 Aplasia cutis congenita is a frequent finding in the setting of rudimentary meningocele.1 The clinical presentation of a young child with alopecic areas on the scalp, that may be scar-like is the correlate of aplasia cutis congenita.8 There are several studies describing a hair collar sign characterized by a tuft of hair surrounding the skin lesion.1,8 The hair color sign is not specific for rudimentary meningocele and has been observed in other settings including glial heterotopia, membranous aplasia cutis, and encephalocele. Association of meningothelial hamartoma with a nevus sebaceus has been described.9
Regarding pathogenesis, the similar anatomical distribution of the lesion to neural tube fusion sites support the hypothesis that classic meningocele and rudimentary meningoceles are a continuous spectrum representing the sequelae in most cases of abnormal neural tube closure.2 There should be an attempt to discern whether there is a connection from the lesion subdurally prior to biopsy as this scenario defines the classic meningocele which would require neurosurgical intervention. The rudimentary meningocele is currently categorized as a nonneoplastic lesion with attributes of a malformation that is adequately treated by simple excision.3
Dr Magro is the director of dermatopathology at Weill Cornell Medicine in New York, NY.
Henry M. Spinelli, MD is a Clinical professor of surgery at Weill Cornell Medical College.
Mary D. Le, MD is a Dermatopathology fellow, Memorial Sloan Kettering Cancer Center.
Disclosure: The authors report no relevant financial relationships.
References
1. Battistella M, Guedj N, Fallet-Bianco C, Bodemer C, Brousse N, Fraitag S. The histopathological spectrum of cutaneous meningeal heterotopias: clues and pitfalls. Histopathology. 2011;59(3):407-420.
2. El Shabrawi-Caelen L, White WL, Soyer HP, Kim BS, F IJ, McCalmont TH. Rudimentary meningocele: remnant of a neural tube defect? Arch Dermatol. 2001;137(1):45-50.
3. Marrogi AJ, Swanson, PE, Kyriakos M, Wick MR. Rudimentary meningocele of the skin. Clinicopathologic features and differential diagnosis. J Cutan Pathol. 1991;18(3):178-188.
4. Lopez DA, Silvers DN, Helwing EB. Cutaneous meningiomas–a clinicopathologic study. Cancer. 1974;34(3):728-744.
5. Kiyohara T, Kawami K, Kouraba S, Kumakira M, Immamura Y. Dented rudimentary meningocele. J Am Acad Dermatol. 2007;57(6):1101-1102.
6. Lu C, Chan YC, Lai CH, Kuo TT, Hong HS. Rudimentary meningocele of the scalp. Dermatol Sinica. 2003;21(4):394-401.
7. Sibley DA, Cooper PH. Rudimentary meningocele: A variant of ‘primary cutaneous meningioma’. J Cutan Pathol. 1989;16(2):72-80.
8. Kenyon K, Zedek D, Sayed C. Incidental finding of cutaneous meningeal heterotopia in aplasia cutis congenita. J Cutan Pathol. 2016:43(7):609-612.
9. Crittenden SC, Sonnier GB. Meningothelial hamartoma associated with nevus sebaceus. Pediatr Dermatol. 2014;31(2):208-211.
This article describes a case of rudimentary meningocele occurring in association with aplasia cutis congenita and focal dermal melanocytosis. Rudimentary meningocele, although considered a form of cutaneous meningioma, is a development anomaly reflecting a form of neural dysraphism. In this regard, other names have been applied to these lesions and likely all are preferred designations over cutaneous meningioma including meningothelial hamartoma, sequestrated meningocele, cutaneous heterotopic meningeal nodules, and acoelic meningeal hamartoma.1-3 Its basis is distinct displacement heterotopia reflective of an embryonic defect in neural tube closure.
Case History
An 8-year-old girl presented with an indeterminate congenital scalp tumor with the clinical impression of nevus sebaceous. Clinical examination revealed a depressed area in the scalp accompanied by localized hair loss. Skull imaging prior to surgery revealed no significant abnormalities. The child was otherwise healthy with no significant past medical history.
With light microscopy, the excision specimen revealed a grossly brown lesion measuring 0.4 × 0.5 cm. Microscopically, there was a complete absence of any adnexal structures accompanied by laminated fibroplasia typical of congenital aplasia cutis (Figure 1). An additional feature was one of dermal melanocytosis defined by a proliferation of slender pigment laden benign dendritic melanocytes within the dermis. In regards to the fibroplasia, the dermis had a hyalinizing quality resulting in expansion of the deeper dermal collagen bundles and interlobular septa within the fat lobule. Within the deeper dermis and subcutaneous fat, monomorphic appearing cuboidal cells with rounded nuclei and a finely dispersed chromatin were noted. The pattern of infiltration was most distinctive whereby this unusual cell population scaffolded along spaces recapitulating a well-differentiated vasoformative lesion. Focally the cells assumed an almost syncytial multinucleated growth pattern in the zones of sinusoidal growth.
However, careful inspection of these spaces suggested that they were pseudovascular sinusoidal-like channels as opposed to representing true vascular channels typical for a vasoformative neoplasm (Figure 2). Foci of psammomatous calcification were also noted. Immunohistochemical stains showed that the cuboidal lining cells were extensively epithelial membrane antigen positive but do not demonstrate any positivity with endothelial cell markers, specifically CD34, CD31, ERG, and factor VIII (Figures 3 and 4). Significant immunoreactivity is not identified for factor-XIIIA, S-100, or Melan-A.
Discussion
Rudimentary meningocele represents a specific subset of neural dysraphism. Other terms for this rare malformation is atretic meningocele and heterotopic meningothelial nodule. The broad topic of meningeal elements in the skin was first discussed by Lopez and colleagues4 in 1974. In this seminal paper, the authors reviewed 25 cases of cutaneous meningioma. The authors proposed a classification scheme that still holds practical value today, recognizing 3 groups: Type I: primary cutaneous meningioma; Type II: ectopic meningioma of the soft tissue with extension into the skin most commonly arising from the proximal peripheral nerves and found reproducibly in the orbit, face, and sinonasal tract typically occurring in adults; and Type III: central nervous system (CNS) meningioma with extension into the skin.4 Type I occurs on the scalp, face, or paravertebral region at birth; Type II develops around sensory organs of the head along the cranial and spinal nerves; and Type III occurs on the face, temple, and scalp.4,5
Lu and colleagues6 described 5 cases of rudimentary meningoceles that were congenital and presented as alopecic lesions on the occipital area. One could consider a rudimentary meningocele as a form of Type I cutaneous meningioma, representing a displacement of meningothelial cells typically occurring in the parietal occipital scalp region or anywhere along the rachidian axis. In atretic/rudimentary meningoceles there is typically no patent connection with the CNS; there may be a defect in the skull or a fibrous tract contiguous with the intracranial cavity. Kiyohara and colleagues5 described a rudimentary meningocele that presented as “dented” skull defect similar to our case. Other presentations include nodules or plaques on the scalp (temporal, parietal, occipital, paramedian, or lumbosacral). Sibley and Cooper7 discussed 5 primary cutaneous meningiomas with a skull defect deep to one lesion and another lesion that presented as a lumbar polyp that was attached to the dura. Angiomas may be adjacent.1
The morphology of the rudimentary meningocele is most commonly in the context of a lesion that has a histology most reminiscent of giant cell fibroblastoma, the hallmarks being in the context of deep seated irregular spaces lined by epithelial appearing cells typically with a multinucleated syncytial appearance. Calcification or psammoma-like bodies and cyst-like areas may be present. As with this case, additional abnormalities such as congenital aplasia cutis and dermal melanocytosis can be observed. Immunohistochemistry stains that are usually employed during workup include positive stains (EMA, NSE, vimentin, neurofilament) and negative stains (CAM5.2, AE1/AE3, cytokeratin, S-100, CD31, CD34, GFAP, CD57, smooth muscle actin, desmin, CD68). Recently reported is the expression of podoplanin and NKI-C3 and to a lesser extent PR and Glut-11.
Histologically, these lesions should be distinguished from hamartomas with ectopic meningothelial elements as well as giant cell fibroblastomas as they have prognostic differences from rudimentary meningocele. In regards to giant cell fibroblastoma, these neoplasms typically occur in younger patients where they present as slow growing neoplasms that have the potential to recur but not metastasize. They are cytogenetically related to dermatofibrosarcoma protuberans with a similar supernumerary ring chromosome derived from chromosomes 17 and 22. While there is a significant degree of light microscopic similitude between the giant cell fibroblastoma and the rudimentary meningocele, the phenotypic profile certainly allows unequivocal distinction between giant cell fibroblastoma and the rudimentary meningocele. In the hamartoma with ectopic meningothelial elements, patients vary in age at the time of presentation but usually the patients are children and young adults with most lesions occurring on the scalp. One observes a constellation of haphazardly arranged bundles of collagen, adipose tissue, nerves, skeletal muscle, and meningothelial cells. The meningothelial cells assume the same atypical infiltrative vasoformative pattern encountered in rudimentary meningocele, and therefore, simulates giant cell fibroblastoma or in an older individual would suggest an angiosarcoma, especially in cases where the lining cells appear somewhat spindled in appearance.
The patients are typically young children presenting with nodules or areas of induration.3 Aplasia cutis congenita is a frequent finding in the setting of rudimentary meningocele.1 The clinical presentation of a young child with alopecic areas on the scalp, that may be scar-like is the correlate of aplasia cutis congenita.8 There are several studies describing a hair collar sign characterized by a tuft of hair surrounding the skin lesion.1,8 The hair color sign is not specific for rudimentary meningocele and has been observed in other settings including glial heterotopia, membranous aplasia cutis, and encephalocele. Association of meningothelial hamartoma with a nevus sebaceus has been described.9
Regarding pathogenesis, the similar anatomical distribution of the lesion to neural tube fusion sites support the hypothesis that classic meningocele and rudimentary meningoceles are a continuous spectrum representing the sequelae in most cases of abnormal neural tube closure.2 There should be an attempt to discern whether there is a connection from the lesion subdurally prior to biopsy as this scenario defines the classic meningocele which would require neurosurgical intervention. The rudimentary meningocele is currently categorized as a nonneoplastic lesion with attributes of a malformation that is adequately treated by simple excision.3
Dr Magro is the director of dermatopathology at Weill Cornell Medicine in New York, NY.
Henry M. Spinelli, MD is a Clinical professor of surgery at Weill Cornell Medical College.
Mary D. Le, MD is a Dermatopathology fellow, Memorial Sloan Kettering Cancer Center.
Disclosure: The authors report no relevant financial relationships.
References
1. Battistella M, Guedj N, Fallet-Bianco C, Bodemer C, Brousse N, Fraitag S. The histopathological spectrum of cutaneous meningeal heterotopias: clues and pitfalls. Histopathology. 2011;59(3):407-420.
2. El Shabrawi-Caelen L, White WL, Soyer HP, Kim BS, F IJ, McCalmont TH. Rudimentary meningocele: remnant of a neural tube defect? Arch Dermatol. 2001;137(1):45-50.
3. Marrogi AJ, Swanson, PE, Kyriakos M, Wick MR. Rudimentary meningocele of the skin. Clinicopathologic features and differential diagnosis. J Cutan Pathol. 1991;18(3):178-188.
4. Lopez DA, Silvers DN, Helwing EB. Cutaneous meningiomas–a clinicopathologic study. Cancer. 1974;34(3):728-744.
5. Kiyohara T, Kawami K, Kouraba S, Kumakira M, Immamura Y. Dented rudimentary meningocele. J Am Acad Dermatol. 2007;57(6):1101-1102.
6. Lu C, Chan YC, Lai CH, Kuo TT, Hong HS. Rudimentary meningocele of the scalp. Dermatol Sinica. 2003;21(4):394-401.
7. Sibley DA, Cooper PH. Rudimentary meningocele: A variant of ‘primary cutaneous meningioma’. J Cutan Pathol. 1989;16(2):72-80.
8. Kenyon K, Zedek D, Sayed C. Incidental finding of cutaneous meningeal heterotopia in aplasia cutis congenita. J Cutan Pathol. 2016:43(7):609-612.
9. Crittenden SC, Sonnier GB. Meningothelial hamartoma associated with nevus sebaceus. Pediatr Dermatol. 2014;31(2):208-211.
Discussion
Rudimentary meningocele represents a specific subset of neural dysraphism. Other terms for this rare malformation is atretic meningocele and heterotopic meningothelial nodule. The broad topic of meningeal elements in the skin was first discussed by Lopez and colleagues4 in 1974. In this seminal paper, the authors reviewed 25 cases of cutaneous meningioma. The authors proposed a classification scheme that still holds practical value today, recognizing 3 groups: Type I: primary cutaneous meningioma; Type II: ectopic meningioma of the soft tissue with extension into the skin most commonly arising from the proximal peripheral nerves and found reproducibly in the orbit, face, and sinonasal tract typically occurring in adults; and Type III: central nervous system (CNS) meningioma with extension into the skin.4 Type I occurs on the scalp, face, or paravertebral region at birth; Type II develops around sensory organs of the head along the cranial and spinal nerves; and Type III occurs on the face, temple, and scalp.4,5
Lu and colleagues6 described 5 cases of rudimentary meningoceles that were congenital and presented as alopecic lesions on the occipital area. One could consider a rudimentary meningocele as a form of Type I cutaneous meningioma, representing a displacement of meningothelial cells typically occurring in the parietal occipital scalp region or anywhere along the rachidian axis. In atretic/rudimentary meningoceles there is typically no patent connection with the CNS; there may be a defect in the skull or a fibrous tract contiguous with the intracranial cavity. Kiyohara and colleagues5 described a rudimentary meningocele that presented as “dented” skull defect similar to our case. Other presentations include nodules or plaques on the scalp (temporal, parietal, occipital, paramedian, or lumbosacral). Sibley and Cooper7 discussed 5 primary cutaneous meningiomas with a skull defect deep to one lesion and another lesion that presented as a lumbar polyp that was attached to the dura. Angiomas may be adjacent.1
The morphology of the rudimentary meningocele is most commonly in the context of a lesion that has a histology most reminiscent of giant cell fibroblastoma, the hallmarks being in the context of deep seated irregular spaces lined by epithelial appearing cells typically with a multinucleated syncytial appearance. Calcification or psammoma-like bodies and cyst-like areas may be present. As with this case, additional abnormalities such as congenital aplasia cutis and dermal melanocytosis can be observed. Immunohistochemistry stains that are usually employed during workup include positive stains (EMA, NSE, vimentin, neurofilament) and negative stains (CAM5.2, AE1/AE3, cytokeratin, S-100, CD31, CD34, GFAP, CD57, smooth muscle actin, desmin, CD68). Recently reported is the expression of podoplanin and NKI-C3 and to a lesser extent PR and Glut-11.
Histologically, these lesions should be distinguished from hamartomas with ectopic meningothelial elements as well as giant cell fibroblastomas as they have prognostic differences from rudimentary meningocele. In regards to giant cell fibroblastoma, these neoplasms typically occur in younger patients where they present as slow growing neoplasms that have the potential to recur but not metastasize. They are cytogenetically related to dermatofibrosarcoma protuberans with a similar supernumerary ring chromosome derived from chromosomes 17 and 22. While there is a significant degree of light microscopic similitude between the giant cell fibroblastoma and the rudimentary meningocele, the phenotypic profile certainly allows unequivocal distinction between giant cell fibroblastoma and the rudimentary meningocele. In the hamartoma with ectopic meningothelial elements, patients vary in age at the time of presentation but usually the patients are children and young adults with most lesions occurring on the scalp. One observes a constellation of haphazardly arranged bundles of collagen, adipose tissue, nerves, skeletal muscle, and meningothelial cells. The meningothelial cells assume the same atypical infiltrative vasoformative pattern encountered in rudimentary meningocele, and therefore, simulates giant cell fibroblastoma or in an older individual would suggest an angiosarcoma, especially in cases where the lining cells appear somewhat spindled in appearance.
The patients are typically young children presenting with nodules or areas of induration.3 Aplasia cutis congenita is a frequent finding in the setting of rudimentary meningocele.1 The clinical presentation of a young child with alopecic areas on the scalp, that may be scar-like is the correlate of aplasia cutis congenita.8 There are several studies describing a hair collar sign characterized by a tuft of hair surrounding the skin lesion.1,8 The hair color sign is not specific for rudimentary meningocele and has been observed in other settings including glial heterotopia, membranous aplasia cutis, and encephalocele. Association of meningothelial hamartoma with a nevus sebaceus has been described.9
Regarding pathogenesis, the similar anatomical distribution of the lesion to neural tube fusion sites support the hypothesis that classic meningocele and rudimentary meningoceles are a continuous spectrum representing the sequelae in most cases of abnormal neural tube closure.2 There should be an attempt to discern whether there is a connection from the lesion subdurally prior to biopsy as this scenario defines the classic meningocele which would require neurosurgical intervention. The rudimentary meningocele is currently categorized as a nonneoplastic lesion with attributes of a malformation that is adequately treated by simple excision.3
Dr Magro is the director of dermatopathology at Weill Cornell Medicine in New York, NY.
Henry M. Spinelli, MD is a Clinical professor of surgery at Weill Cornell Medical College.
Mary D. Le, MD is a Dermatopathology fellow, Memorial Sloan Kettering Cancer Center.
Disclosure: The authors report no relevant financial relationships.
References
1. Battistella M, Guedj N, Fallet-Bianco C, Bodemer C, Brousse N, Fraitag S. The histopathological spectrum of cutaneous meningeal heterotopias: clues and pitfalls. Histopathology. 2011;59(3):407-420.
2. El Shabrawi-Caelen L, White WL, Soyer HP, Kim BS, F IJ, McCalmont TH. Rudimentary meningocele: remnant of a neural tube defect? Arch Dermatol. 2001;137(1):45-50.
3. Marrogi AJ, Swanson, PE, Kyriakos M, Wick MR. Rudimentary meningocele of the skin. Clinicopathologic features and differential diagnosis. J Cutan Pathol. 1991;18(3):178-188.
4. Lopez DA, Silvers DN, Helwing EB. Cutaneous meningiomas–a clinicopathologic study. Cancer. 1974;34(3):728-744.
5. Kiyohara T, Kawami K, Kouraba S, Kumakira M, Immamura Y. Dented rudimentary meningocele. J Am Acad Dermatol. 2007;57(6):1101-1102.
6. Lu C, Chan YC, Lai CH, Kuo TT, Hong HS. Rudimentary meningocele of the scalp. Dermatol Sinica. 2003;21(4):394-401.
7. Sibley DA, Cooper PH. Rudimentary meningocele: A variant of ‘primary cutaneous meningioma’. J Cutan Pathol. 1989;16(2):72-80.
8. Kenyon K, Zedek D, Sayed C. Incidental finding of cutaneous meningeal heterotopia in aplasia cutis congenita. J Cutan Pathol. 2016:43(7):609-612.
9. Crittenden SC, Sonnier GB. Meningothelial hamartoma associated with nevus sebaceus. Pediatr Dermatol. 2014;31(2):208-211.
