A 74-year-old otherwise healthy woman presented to an outpatient dermatology clinic for an annual skin evaluation. She denied family or personal history of skin cancer as well as any other current physical illness or distress. Physical examination involving sun-exposed skin areas (sparing head) revealed multiple annular patches with central atrophy, slight erythema, and a well-demarcated fine scaly border (Figures 1A-B). Lesions ranged 5 to 35 mm in diameter. The patient reported that the lesions were present since the third decade of life. There were no associated symptoms. Her condition worsened during months of increased UV radiation, particularly April through October. No other relatives had a similar skin condition. Prior to presentation, the patient received no treatment for the condition.
What is your diagnosis?
Go to page 2 for an answer and more details.
{{pagebreak}}
Diagnosis: Disseminated Superficial Actinic Porokeratosis
Disseminated superficial actinic porokeratosis (DSAP) is a chronic and progressive condition characterized by abnormal keratinization.1 The thin papules or plaques are demarcated by a keratotic furrowed rim of scale that expands centrifugally and classically presents on the legs of adult women. It is the most common presentation of at least 5 distinct clinical variants of porokeratosis, all of which share the distinctive hyperkeratotic ridge-like border known as the cornoid lamella.1
Mibelli first described classic porokeratosis in 1893.1 In the same year, Respighi reported the superficial and disseminated presentation of the condition. It was later learned that porokeratosis was a misnomer, based on the original assumption that the cornoid lamella arose from pores of sweat glands.1
Clinical Presentation
Porokeratosis is an uncommon skin condition that begins with a small, red or brown slightly raised verruciform papule usually around a hair follicle. The lesion slowly enlarges to a patch over time, leaving an atrophic center with the surrounding cornoid lamella. Lesions can proliferate, developing into DSAP, where they are classically confined to sun-exposed, symmetrical areas of the extensor surfaces of the extremities, shoulders, and back (Figures 1A and B).
Only 15% of DSAP patients report facial lesions.2 Lesions are typically asymptomatic and sweating is absent within the lesion, but one-third of patients report pruritus or a stinging sensation.3 UV light exposure can exacerbate the condition, and cases of DSAP in patients receiving UV therapy for psoriasis have been described.4
Epidemiology
While the exact prevalence of DSAP is unknown, it is deemed an uncommon skin condition by the Genetic and Rare Diseases Information Center because fewer than 200,000 are affected in the United States.5
DSAP is the most common type of porokeratosis and can present at any age, but typically arises in the third to fourth decade of life with a slight female preponderance (1.76:1).6
Pathogenesis and Histology
The pathogenesis of DSAP is not well understood. Mutations in several chromosomal loci have been mapped, and MVK and SART3 genes identified, with an autosomal dominant pattern of inheritance and a reduced penetrance at a younger age.7,8
There are 4 known possible genetic loci: 12q23.3 (DSAP1), 15q25.1-26.1 (DSAP2), 1p31.3-p31.1 (DSAP3), and 18p11.3 (DSAP4). Other risk factors for DSAP include fair skin, p53 overexpression, UV exposure, and immunosuppression.9
The histologic appearance on scanning power view shows a hyperkeratotic lesion with parakeratotic columns at the margins. The cornoid lamella is a diagnostic feature, seen as a parakeratotic column with an underlying vertical zone of dyskeratotic and vacuolated cells contained within the epidermis and focal loss of the granular layer. Mild lymphocytic infiltrate and angioplasia may be present in the underlying dermis.
Treatment
Treatment of DSAP is an important consideration because of its classification as a premalignant condition, though some may choose to forego it due to the inconsistent efficacy.10 Trigger factors identified for the development of malignancy in the lesions include UV radiation, electron beam therapy, radiation beam therapy, and immunosuppression.10,11
Skin cancer surveillance should be continued on a regular basis. Treatment options include keratolytic treatments, 5-fluorouracil 5% strength, topical imiquimod, diclofenac gel, topical retinoids, cryotherapy, photodynamic therapy, der-mabrasion, shave excision, curettage, and linear excisions. Because no single treatment has proven superior, the decision should be based on patient preference. Because of the association of DSAP with UV exposure, both in the development and progression to malignancy, education on the importance of sun protection, and regular skin examinations is essential in patients with the disease and those with a positive family history.
Our Patient
The patient presentation at initial evaluation was typical of chronic DSAP, however, other potential etiologies and malignant transformation need to be excluded (Table 1).
Biopsy of 1 lesion suspicious for malignant transformation was collected. Sections from a shave biopsy specimen showed hyperkeratosis with columns of parakeratosis, and presence of limited premature keratinization and foci of lichenoid inflammation, consistent with porokeratosis (Figures 2 A-D).
Extensive discussion about the importance of sun avoidance, proper skin cancer surveillance, and the potential for malignant transformation was conducted.
The patient agreed to return for follow-up and have possible treatment with 5-fluorouracil cream to the widespread lesions on the extremities. Liquid nitrogen treatment and surgical options were also presented for individual potentially premalignant or malignant lesions pending biopsy results.
Conclusion
Our case represents a typical presentation of DSAP which has a low malignancy transformation potential. It is important to distinguish DSAP from other subtypes of parakeratoses (Table 2), mimicking conditions, and also to exclude malignancy arising within some of the lesions.
Biopsy should be prompted by clinical suspicion of malignant transformation in 1 of the lesions and to confirm the diagnosis. Close cancer surveillance and regular follow-up are necessary along with education about sun avoidance.
The patient should be informed about the chronicity of the condition and unavailability of complete cosmetic resolution.
Dr Demidova is with Kansas City University/Tri-County Dermatology in Cuyahoga Falls, OH.Ms Giesey is a student at Ohio University College of Osteopathic Medicine in Athens, OH.
Dr Fox is with Kansas City University/Tri-County Dermatology in Cuyahoga Falls, OH.
Disclosure: The authors report no relevant financial relationships.
References
1. D’souza P, Dhali T, Arora S, Gupta H, Khanna U. Porokeratosis ptychotropica: a rare variant of porokeratosis. Dermatology Online J. 2014;20:6.
2. Lee Y, Choi EH. Exclusive facial porokeratosis: histopathologically showing follicular cornoid lamellae. J Dermatol. 2011;38(11):1072-1075.
3. Sertznig P, von Felbert V, Megahed M. Porokeratosis: present concepts. J Eur Acad Dermatol Venerol. 2012;26(4):404-412.
4. Kawara S, Oiso N, Kawada A. Disseminated superficial actinic porokeratosis in a patient undergoing treatment with long-term narrowband ultraviolet B for psoriasis. J Dermatol. 2011;38(6):585-587.
5. Disseminated superficial actinic porokeratosis. Genetic and Rare Diseases Information Center website. https://rarediseases.info.nih.gov. Updated November 1, 2017. Accessed November 3, 2017.
6. Murase J, Gilliam AC. Disseminated superficial actinic porokeratosis co-existing with linear and verrucous porokeratosis in an elderly woman: update on the genetics and clinical expression of porokeratosis. J Am Acad Dermatol. 2009;63(5):886-891.
7. Xia K, Deng H, Xia JH, et al. A novel locus (DSAP2) for disseminated superficial actinic porokeratosis maps to chromosome 15q25.1-26.1. Br J Dermatol. 2002;147(4):650-654.
8. Liu Y, Wang J, Qin Y, et al. Identification of three mutations in the MVK gene in six patients associated with disseminated superficial actinic porokeratosis. Clin Chim Acta. 2016;454:124-129.
9. Ninomiya Y, Urano Y, Yoshimoto K, et al. p53 gene mutation analysis in porokeratosis and porokeratosis-associated squamous cell carcinoma. J Dermatol Sci. 1997;14(3):173-178.
10. Breneman DL, Breneman JC. Cutaneous T-cell lymphoma mimicking porokeratosis of Mibelli. J Am Acad Dermatol. 1993;29(6):1046-1048.
11. Wolff S. Porokeratosis. In: Irwin F, Eisen AZ, Wolff K, eds. Fitzpatrick’s Dermatology in General Medicine. Vol. 1. New York, NY: McGraw-Hill; 2003:532-537.
12. Bolognia J, Jorizzo J, Rapini R, eds. Dermatology. Vol 2. Maryland Heights, MO: Mosby; 2007.
13. Weedon D. Weedon’s Skin Pathology. 3rd ed. London, United Kingdom: Churchill Livingstone Elsevier; 2010.
A 74-year-old otherwise healthy woman presented to an outpatient dermatology clinic for an annual skin evaluation. She denied family or personal history of skin cancer as well as any other current physical illness or distress. Physical examination involving sun-exposed skin areas (sparing head) revealed multiple annular patches with central atrophy, slight erythema, and a well-demarcated fine scaly border (Figures 1A-B). Lesions ranged 5 to 35 mm in diameter. The patient reported that the lesions were present since the third decade of life. There were no associated symptoms. Her condition worsened during months of increased UV radiation, particularly April through October. No other relatives had a similar skin condition. Prior to presentation, the patient received no treatment for the condition.
What is your diagnosis?
Go to page 2 for an answer and more details.
{{pagebreak}}
Diagnosis: Disseminated Superficial Actinic Porokeratosis
Disseminated superficial actinic porokeratosis (DSAP) is a chronic and progressive condition characterized by abnormal keratinization.1 The thin papules or plaques are demarcated by a keratotic furrowed rim of scale that expands centrifugally and classically presents on the legs of adult women. It is the most common presentation of at least 5 distinct clinical variants of porokeratosis, all of which share the distinctive hyperkeratotic ridge-like border known as the cornoid lamella.1
Mibelli first described classic porokeratosis in 1893.1 In the same year, Respighi reported the superficial and disseminated presentation of the condition. It was later learned that porokeratosis was a misnomer, based on the original assumption that the cornoid lamella arose from pores of sweat glands.1
Clinical Presentation
Porokeratosis is an uncommon skin condition that begins with a small, red or brown slightly raised verruciform papule usually around a hair follicle. The lesion slowly enlarges to a patch over time, leaving an atrophic center with the surrounding cornoid lamella. Lesions can proliferate, developing into DSAP, where they are classically confined to sun-exposed, symmetrical areas of the extensor surfaces of the extremities, shoulders, and back (Figures 1A and B).
Only 15% of DSAP patients report facial lesions.2 Lesions are typically asymptomatic and sweating is absent within the lesion, but one-third of patients report pruritus or a stinging sensation.3 UV light exposure can exacerbate the condition, and cases of DSAP in patients receiving UV therapy for psoriasis have been described.4
Epidemiology
While the exact prevalence of DSAP is unknown, it is deemed an uncommon skin condition by the Genetic and Rare Diseases Information Center because fewer than 200,000 are affected in the United States.5
DSAP is the most common type of porokeratosis and can present at any age, but typically arises in the third to fourth decade of life with a slight female preponderance (1.76:1).6
Pathogenesis and Histology
The pathogenesis of DSAP is not well understood. Mutations in several chromosomal loci have been mapped, and MVK and SART3 genes identified, with an autosomal dominant pattern of inheritance and a reduced penetrance at a younger age.7,8
There are 4 known possible genetic loci: 12q23.3 (DSAP1), 15q25.1-26.1 (DSAP2), 1p31.3-p31.1 (DSAP3), and 18p11.3 (DSAP4). Other risk factors for DSAP include fair skin, p53 overexpression, UV exposure, and immunosuppression.9
The histologic appearance on scanning power view shows a hyperkeratotic lesion with parakeratotic columns at the margins. The cornoid lamella is a diagnostic feature, seen as a parakeratotic column with an underlying vertical zone of dyskeratotic and vacuolated cells contained within the epidermis and focal loss of the granular layer. Mild lymphocytic infiltrate and angioplasia may be present in the underlying dermis.
Treatment
Treatment of DSAP is an important consideration because of its classification as a premalignant condition, though some may choose to forego it due to the inconsistent efficacy.10 Trigger factors identified for the development of malignancy in the lesions include UV radiation, electron beam therapy, radiation beam therapy, and immunosuppression.10,11
Skin cancer surveillance should be continued on a regular basis. Treatment options include keratolytic treatments, 5-fluorouracil 5% strength, topical imiquimod, diclofenac gel, topical retinoids, cryotherapy, photodynamic therapy, der-mabrasion, shave excision, curettage, and linear excisions. Because no single treatment has proven superior, the decision should be based on patient preference. Because of the association of DSAP with UV exposure, both in the development and progression to malignancy, education on the importance of sun protection, and regular skin examinations is essential in patients with the disease and those with a positive family history.
Our Patient
The patient presentation at initial evaluation was typical of chronic DSAP, however, other potential etiologies and malignant transformation need to be excluded (Table 1).
Biopsy of 1 lesion suspicious for malignant transformation was collected. Sections from a shave biopsy specimen showed hyperkeratosis with columns of parakeratosis, and presence of limited premature keratinization and foci of lichenoid inflammation, consistent with porokeratosis (Figures 2 A-D).
Extensive discussion about the importance of sun avoidance, proper skin cancer surveillance, and the potential for malignant transformation was conducted.
The patient agreed to return for follow-up and have possible treatment with 5-fluorouracil cream to the widespread lesions on the extremities. Liquid nitrogen treatment and surgical options were also presented for individual potentially premalignant or malignant lesions pending biopsy results.
Conclusion
Our case represents a typical presentation of DSAP which has a low malignancy transformation potential. It is important to distinguish DSAP from other subtypes of parakeratoses (Table 2), mimicking conditions, and also to exclude malignancy arising within some of the lesions.
Biopsy should be prompted by clinical suspicion of malignant transformation in 1 of the lesions and to confirm the diagnosis. Close cancer surveillance and regular follow-up are necessary along with education about sun avoidance.
The patient should be informed about the chronicity of the condition and unavailability of complete cosmetic resolution.
Dr Demidova is with Kansas City University/Tri-County Dermatology in Cuyahoga Falls, OH.
Ms Giesey is a student at Ohio University College of Osteopathic Medicine in Athens, OH.
Dr Fox is with Kansas City University/Tri-County Dermatology in Cuyahoga Falls, OH.
Disclosure: The authors report no relevant financial relationships.
References
1. D’souza P, Dhali T, Arora S, Gupta H, Khanna U. Porokeratosis ptychotropica: a rare variant of porokeratosis. Dermatology Online J. 2014;20:6.
2. Lee Y, Choi EH. Exclusive facial porokeratosis: histopathologically showing follicular cornoid lamellae. J Dermatol. 2011;38(11):1072-1075.
3. Sertznig P, von Felbert V, Megahed M. Porokeratosis: present concepts. J Eur Acad Dermatol Venerol. 2012;26(4):404-412.
4. Kawara S, Oiso N, Kawada A. Disseminated superficial actinic porokeratosis in a patient undergoing treatment with long-term narrowband ultraviolet B for psoriasis. J Dermatol. 2011;38(6):585-587.
5. Disseminated superficial actinic porokeratosis. Genetic and Rare Diseases Information Center website. https://rarediseases.info.nih.gov. Updated November 1, 2017. Accessed November 3, 2017.
6. Murase J, Gilliam AC. Disseminated superficial actinic porokeratosis co-existing with linear and verrucous porokeratosis in an elderly woman: update on the genetics and clinical expression of porokeratosis. J Am Acad Dermatol. 2009;63(5):886-891.
7. Xia K, Deng H, Xia JH, et al. A novel locus (DSAP2) for disseminated superficial actinic porokeratosis maps to chromosome 15q25.1-26.1. Br J Dermatol. 2002;147(4):650-654.
8. Liu Y, Wang J, Qin Y, et al. Identification of three mutations in the MVK gene in six patients associated with disseminated superficial actinic porokeratosis. Clin Chim Acta. 2016;454:124-129.
9. Ninomiya Y, Urano Y, Yoshimoto K, et al. p53 gene mutation analysis in porokeratosis and porokeratosis-associated squamous cell carcinoma. J Dermatol Sci. 1997;14(3):173-178.
10. Breneman DL, Breneman JC. Cutaneous T-cell lymphoma mimicking porokeratosis of Mibelli. J Am Acad Dermatol. 1993;29(6):1046-1048.
11. Wolff S. Porokeratosis. In: Irwin F, Eisen AZ, Wolff K, eds. Fitzpatrick’s Dermatology in General Medicine. Vol. 1. New York, NY: McGraw-Hill; 2003:532-537.
12. Bolognia J, Jorizzo J, Rapini R, eds. Dermatology. Vol 2. Maryland Heights, MO: Mosby; 2007.
13. Weedon D. Weedon’s Skin Pathology. 3rd ed. London, United Kingdom: Churchill Livingstone Elsevier; 2010.
A 74-year-old otherwise healthy woman presented to an outpatient dermatology clinic for an annual skin evaluation. She denied family or personal history of skin cancer as well as any other current physical illness or distress. Physical examination involving sun-exposed skin areas (sparing head) revealed multiple annular patches with central atrophy, slight erythema, and a well-demarcated fine scaly border (Figures 1A-B). Lesions ranged 5 to 35 mm in diameter. The patient reported that the lesions were present since the third decade of life. There were no associated symptoms. Her condition worsened during months of increased UV radiation, particularly April through October. No other relatives had a similar skin condition. Prior to presentation, the patient received no treatment for the condition.
What is your diagnosis?
Go to page 2 for an answer and more details.
{{pagebreak}}
Diagnosis: Disseminated Superficial Actinic Porokeratosis
Disseminated superficial actinic porokeratosis (DSAP) is a chronic and progressive condition characterized by abnormal keratinization.1 The thin papules or plaques are demarcated by a keratotic furrowed rim of scale that expands centrifugally and classically presents on the legs of adult women. It is the most common presentation of at least 5 distinct clinical variants of porokeratosis, all of which share the distinctive hyperkeratotic ridge-like border known as the cornoid lamella.1
Mibelli first described classic porokeratosis in 1893.1 In the same year, Respighi reported the superficial and disseminated presentation of the condition. It was later learned that porokeratosis was a misnomer, based on the original assumption that the cornoid lamella arose from pores of sweat glands.1
Clinical Presentation
Porokeratosis is an uncommon skin condition that begins with a small, red or brown slightly raised verruciform papule usually around a hair follicle. The lesion slowly enlarges to a patch over time, leaving an atrophic center with the surrounding cornoid lamella. Lesions can proliferate, developing into DSAP, where they are classically confined to sun-exposed, symmetrical areas of the extensor surfaces of the extremities, shoulders, and back (Figures 1A and B).
Only 15% of DSAP patients report facial lesions.2 Lesions are typically asymptomatic and sweating is absent within the lesion, but one-third of patients report pruritus or a stinging sensation.3 UV light exposure can exacerbate the condition, and cases of DSAP in patients receiving UV therapy for psoriasis have been described.4
Epidemiology
While the exact prevalence of DSAP is unknown, it is deemed an uncommon skin condition by the Genetic and Rare Diseases Information Center because fewer than 200,000 are affected in the United States.5
DSAP is the most common type of porokeratosis and can present at any age, but typically arises in the third to fourth decade of life with a slight female preponderance (1.76:1).6
Pathogenesis and Histology
The pathogenesis of DSAP is not well understood. Mutations in several chromosomal loci have been mapped, and MVK and SART3 genes identified, with an autosomal dominant pattern of inheritance and a reduced penetrance at a younger age.7,8
There are 4 known possible genetic loci: 12q23.3 (DSAP1), 15q25.1-26.1 (DSAP2), 1p31.3-p31.1 (DSAP3), and 18p11.3 (DSAP4). Other risk factors for DSAP include fair skin, p53 overexpression, UV exposure, and immunosuppression.9
The histologic appearance on scanning power view shows a hyperkeratotic lesion with parakeratotic columns at the margins. The cornoid lamella is a diagnostic feature, seen as a parakeratotic column with an underlying vertical zone of dyskeratotic and vacuolated cells contained within the epidermis and focal loss of the granular layer. Mild lymphocytic infiltrate and angioplasia may be present in the underlying dermis.
Treatment
Treatment of DSAP is an important consideration because of its classification as a premalignant condition, though some may choose to forego it due to the inconsistent efficacy.10 Trigger factors identified for the development of malignancy in the lesions include UV radiation, electron beam therapy, radiation beam therapy, and immunosuppression.10,11
Skin cancer surveillance should be continued on a regular basis. Treatment options include keratolytic treatments, 5-fluorouracil 5% strength, topical imiquimod, diclofenac gel, topical retinoids, cryotherapy, photodynamic therapy, der-mabrasion, shave excision, curettage, and linear excisions. Because no single treatment has proven superior, the decision should be based on patient preference. Because of the association of DSAP with UV exposure, both in the development and progression to malignancy, education on the importance of sun protection, and regular skin examinations is essential in patients with the disease and those with a positive family history.
Our Patient
The patient presentation at initial evaluation was typical of chronic DSAP, however, other potential etiologies and malignant transformation need to be excluded (Table 1).
Biopsy of 1 lesion suspicious for malignant transformation was collected. Sections from a shave biopsy specimen showed hyperkeratosis with columns of parakeratosis, and presence of limited premature keratinization and foci of lichenoid inflammation, consistent with porokeratosis (Figures 2 A-D).
Extensive discussion about the importance of sun avoidance, proper skin cancer surveillance, and the potential for malignant transformation was conducted.
The patient agreed to return for follow-up and have possible treatment with 5-fluorouracil cream to the widespread lesions on the extremities. Liquid nitrogen treatment and surgical options were also presented for individual potentially premalignant or malignant lesions pending biopsy results.
Conclusion
Our case represents a typical presentation of DSAP which has a low malignancy transformation potential. It is important to distinguish DSAP from other subtypes of parakeratoses (Table 2), mimicking conditions, and also to exclude malignancy arising within some of the lesions.
Biopsy should be prompted by clinical suspicion of malignant transformation in 1 of the lesions and to confirm the diagnosis. Close cancer surveillance and regular follow-up are necessary along with education about sun avoidance.
The patient should be informed about the chronicity of the condition and unavailability of complete cosmetic resolution.
Dr Demidova is with Kansas City University/Tri-County Dermatology in Cuyahoga Falls, OH.
Ms Giesey is a student at Ohio University College of Osteopathic Medicine in Athens, OH.
Dr Fox is with Kansas City University/Tri-County Dermatology in Cuyahoga Falls, OH.
Disclosure: The authors report no relevant financial relationships.
References
1. D’souza P, Dhali T, Arora S, Gupta H, Khanna U. Porokeratosis ptychotropica: a rare variant of porokeratosis. Dermatology Online J. 2014;20:6.
2. Lee Y, Choi EH. Exclusive facial porokeratosis: histopathologically showing follicular cornoid lamellae. J Dermatol. 2011;38(11):1072-1075.
3. Sertznig P, von Felbert V, Megahed M. Porokeratosis: present concepts. J Eur Acad Dermatol Venerol. 2012;26(4):404-412.
4. Kawara S, Oiso N, Kawada A. Disseminated superficial actinic porokeratosis in a patient undergoing treatment with long-term narrowband ultraviolet B for psoriasis. J Dermatol. 2011;38(6):585-587.
5. Disseminated superficial actinic porokeratosis. Genetic and Rare Diseases Information Center website. https://rarediseases.info.nih.gov. Updated November 1, 2017. Accessed November 3, 2017.
6. Murase J, Gilliam AC. Disseminated superficial actinic porokeratosis co-existing with linear and verrucous porokeratosis in an elderly woman: update on the genetics and clinical expression of porokeratosis. J Am Acad Dermatol. 2009;63(5):886-891.
7. Xia K, Deng H, Xia JH, et al. A novel locus (DSAP2) for disseminated superficial actinic porokeratosis maps to chromosome 15q25.1-26.1. Br J Dermatol. 2002;147(4):650-654.
8. Liu Y, Wang J, Qin Y, et al. Identification of three mutations in the MVK gene in six patients associated with disseminated superficial actinic porokeratosis. Clin Chim Acta. 2016;454:124-129.
9. Ninomiya Y, Urano Y, Yoshimoto K, et al. p53 gene mutation analysis in porokeratosis and porokeratosis-associated squamous cell carcinoma. J Dermatol Sci. 1997;14(3):173-178.
10. Breneman DL, Breneman JC. Cutaneous T-cell lymphoma mimicking porokeratosis of Mibelli. J Am Acad Dermatol. 1993;29(6):1046-1048.
11. Wolff S. Porokeratosis. In: Irwin F, Eisen AZ, Wolff K, eds. Fitzpatrick’s Dermatology in General Medicine. Vol. 1. New York, NY: McGraw-Hill; 2003:532-537.
12. Bolognia J, Jorizzo J, Rapini R, eds. Dermatology. Vol 2. Maryland Heights, MO: Mosby; 2007.
13. Weedon D. Weedon’s Skin Pathology. 3rd ed. London, United Kingdom: Churchill Livingstone Elsevier; 2010.
