PATIENT PRESENTATION
A 71-year-old man presented with this slowly growing soft nodule on his abdomen. He denied any history of skin diseases and family history was unremarkable. On physical examination there was a 1-cm x 1-cm pedunculated nodule with pinpoint hemorrhage on his abdomen. A faint area of hyperpigmentation was also present at its base. The biopsy revealed long, thin, branching strands of cells embedded within a fibrous stroma. Next to some of these strands there were small groups of dark-staining cells in a palisading pattern in the peripheral cell layer.
What is Your Diagnosis?
Diagnosis:
Fibroepithelioma of Pinkus
Despite the debate about its true nature, fibroepithelioma of Pinkus (FEP) is considered a rare variant of basal cell carcinoma (BCC) with an approximate frequency of 0.3% to 1.4%.1,2 FEP most commonly appears on the trunk or thigh,3 unlike the majority of BCCs, which occur on sun-exposed areas such as the face.4 Females have a slightly higher prevalence for FEP as opposed to most BCCs, which occur more frequently in males.5 Similar to other BCCs, this tumor develops most commonly in individuals aged 40 to 60 years old.6
FEP: Benign or Malignant?
In 1953 Herman Pinkus1 made the first description of FEP, calling it a “premalignant fibroepithelial tumor of the skin.” Recently, authors have debated whether this lesion is benign or malignant.5,7 Bowen and Leboit5 conducted a study that concludes FEP is more similar to trichoblastoma, a benign neoplasm with primitive hair follicle differentiation,8 than to BCC, a malignant neoplasm derived from nonkeratinizing cells that originate in the basal layer of the epidermis.9 Their work supports previous studies by Schulz and Hartschuh10 that suggest FEP is closer to benign trichoblastoma due to the occurrence of Merkel cells that appear in FEP as well as in trichoblastoma.11
On the other hand, the authors Ackerman and Gottlieb argue that FEP is not benign or premalignant, but rather a malignant neoplasm derived from trichoblasts, or a trichoblastic (basal cell) carcinoma.7 Controversy regarding FEP as a benign or malignant lesion continues today.
Clinical Features
Individuals present with a sessile, firm, flesh-to-pink-to-red or reddish-brown colored nodule or plaque, usually on their abdomen or thigh.12,13 Patients may have single or multiple lesions9 that clinically resemble a fibroepithelial polyp3 or a broad-based fibroma.13 Cases of FEP have been reported in other areas of the body, including on the sole of the foot,14 penis,15 thorax,16 anus, scrotum,6 and overlying breast skin.17 The development of FEP is higher in areas of previous radiation therapy.6,13 Most FEPs are asymptomatic16 with slow progression.13
Recently Zalaudek et al18 discussed a retrospective case evaluation of 10 FEPs in which they used dermatoscopy to help evaluate the lesions after histological diagnosis. The authors identified what they termed “fine arborizing vessels” in all 10 FEPs.18 These vessels of FEP are smaller in caliber and have less evident ramifications as compared to typical arborizing telangiectasias of BCCs.18 Another key dermatoscopic finding was the presence of white streaks; these were found in nine out of 10 lesions.18 While the authors identified similar features in their case study, they acknowledged the small size of their study and noted that most FEPs are not suspected clinically.
Histology
The histological appearance of FEP is characterized by long, thin, anastomosing branching strands of interwoven basaloid cells that are embedded in a fibrous stroma.1,4,9,13 Many of the strands connect with the surface epidermis.4,13 Two cell types make up the strands: one, a light-staining cell that comprises the majority of cells the other, a dark-staining cell found in scattered small groups alongside the strands with a palisading arrangement of the peripheral cell layer.4,6,13 In some cases, eccrine ducts are found within the strands of basaloid cells, leading to the speculation that FEP may arise from the replacement of these ducts by infiltrating basaloid cells.3,19,20
Normally, the entire lesion is located superficially above the level of the epidermal plane with a well-demarcated lower border.4,13 Rarely, FEP will develop into a more invasive BCC.3 FEP lesions often combine features of an intracanalicular fibroadenoma of the breast, the reticulated type of seborrheic keratosis, and a superficial basal cell carcinoma.4,13 While many FEP lesions bear a strong histological resemblance to reticulated seborrheic keratosis, FEP lesions lack the typical horn and pseudohorn pearls of seborrheic keratosis.6 Recent case reports described FEP with giant cells21 and a pigmented variant of FEP.12
Special stains have been used in an attempt to classify FEP as a benign or malignant entity. Katona et al22 demonstrated that androgen receptor expression is frequently present in BCC and FEP as compared to benign follicular tumors. These data support the designation of FEP as a variant of BCC.22 However, cytokeratin 20 (CK20), which stains Merkel cells, also has been used to differentiate between BCC and benign follicular tumors.10,23
Su reports a case of a patient with two separate lesions, one a histologically confirmed FEP and the other a BCC. The FEP stained Merkel cell positive (CK20+) while the BCC stained CK20 negative, suggesting that FEP should not be considered a variant of BCC.23
Despite the availability of these special stains, debate continues regarding the benign or malignant classification of FEP.
Differential Diagnoses
While clinical examination may lead to suspected FEP, definite diagnosis requires a biopsy and subsequent histopathological examination.13 Clinical lesions must be differentiated from the following: benign fibroma, seborrheic keratosis, fibroepithelial polyp (acrochordon), amelanotic malignant melanoma, and BCC.13,23
Treatment
The treatment of choice for FEP is complete excision.13 Approaches for removal are similar to other forms of basal cell carcinoma and are case dependent.6 Lesions may be removed by Mohs micrographic surgery (MMS), standard surgical excision, destruction by various modalities, or topical chemotherapy.9
MMS is the treatment of choice for high-risk primary BCC or any recurrent BCC.9 As compared to standard surgical excision, MMS permits maximal conservation of healthy tissue.9 The fibrous stroma portion of FEP makes curettage and cautery more difficult, thus excision is preferred.13 Rarely, intralesional or topical chemotherapy (such as 5-fluorouracil) may be therapeutic.6 Radiation therapy may be considered for patients with FEP who have never received this treatment in the past.13
Prevention
Following the diagnosis and removal of FEP, or any other BCC, patients should be educated regarding the use of sunscreens with a sun protective factor of at least 15, encouraged to avoid peak intensity hours of sun exposure (10 a.m. to 3 p.m.), taught the dangers of artificial tanning, and monitored with close follow-up (at least yearly) by their dermatologists.6
A Good Prognosis
Despite the controversy mentioned earlier, patients with FEP are considered to have a rare subtype of BCC, and with proper diagnosis and treatment, have a good prognosis.9
Further research is required to document the accuracy of dermatoscopy or other more sophisticated diagnostic tools in aiding the clinical diagnosis of FEP.
Our patient had his lesion excised with a thin margin and had no recurrence 1 year later. We recommend continued yearly full-body skin examinations for our patient as well as lifelong sun protection.
PATIENT PRESENTATION
A 71-year-old man presented with this slowly growing soft nodule on his abdomen. He denied any history of skin diseases and family history was unremarkable. On physical examination there was a 1-cm x 1-cm pedunculated nodule with pinpoint hemorrhage on his abdomen. A faint area of hyperpigmentation was also present at its base. The biopsy revealed long, thin, branching strands of cells embedded within a fibrous stroma. Next to some of these strands there were small groups of dark-staining cells in a palisading pattern in the peripheral cell layer.
What is Your Diagnosis?
Diagnosis:
Fibroepithelioma of Pinkus
Despite the debate about its true nature, fibroepithelioma of Pinkus (FEP) is considered a rare variant of basal cell carcinoma (BCC) with an approximate frequency of 0.3% to 1.4%.1,2 FEP most commonly appears on the trunk or thigh,3 unlike the majority of BCCs, which occur on sun-exposed areas such as the face.4 Females have a slightly higher prevalence for FEP as opposed to most BCCs, which occur more frequently in males.5 Similar to other BCCs, this tumor develops most commonly in individuals aged 40 to 60 years old.6
FEP: Benign or Malignant?
In 1953 Herman Pinkus1 made the first description of FEP, calling it a “premalignant fibroepithelial tumor of the skin.” Recently, authors have debated whether this lesion is benign or malignant.5,7 Bowen and Leboit5 conducted a study that concludes FEP is more similar to trichoblastoma, a benign neoplasm with primitive hair follicle differentiation,8 than to BCC, a malignant neoplasm derived from nonkeratinizing cells that originate in the basal layer of the epidermis.9 Their work supports previous studies by Schulz and Hartschuh10 that suggest FEP is closer to benign trichoblastoma due to the occurrence of Merkel cells that appear in FEP as well as in trichoblastoma.11
On the other hand, the authors Ackerman and Gottlieb argue that FEP is not benign or premalignant, but rather a malignant neoplasm derived from trichoblasts, or a trichoblastic (basal cell) carcinoma.7 Controversy regarding FEP as a benign or malignant lesion continues today.
Clinical Features
Individuals present with a sessile, firm, flesh-to-pink-to-red or reddish-brown colored nodule or plaque, usually on their abdomen or thigh.12,13 Patients may have single or multiple lesions9 that clinically resemble a fibroepithelial polyp3 or a broad-based fibroma.13 Cases of FEP have been reported in other areas of the body, including on the sole of the foot,14 penis,15 thorax,16 anus, scrotum,6 and overlying breast skin.17 The development of FEP is higher in areas of previous radiation therapy.6,13 Most FEPs are asymptomatic16 with slow progression.13
Recently Zalaudek et al18 discussed a retrospective case evaluation of 10 FEPs in which they used dermatoscopy to help evaluate the lesions after histological diagnosis. The authors identified what they termed “fine arborizing vessels” in all 10 FEPs.18 These vessels of FEP are smaller in caliber and have less evident ramifications as compared to typical arborizing telangiectasias of BCCs.18 Another key dermatoscopic finding was the presence of white streaks; these were found in nine out of 10 lesions.18 While the authors identified similar features in their case study, they acknowledged the small size of their study and noted that most FEPs are not suspected clinically.
Histology
The histological appearance of FEP is characterized by long, thin, anastomosing branching strands of interwoven basaloid cells that are embedded in a fibrous stroma.1,4,9,13 Many of the strands connect with the surface epidermis.4,13 Two cell types make up the strands: one, a light-staining cell that comprises the majority of cells the other, a dark-staining cell found in scattered small groups alongside the strands with a palisading arrangement of the peripheral cell layer.4,6,13 In some cases, eccrine ducts are found within the strands of basaloid cells, leading to the speculation that FEP may arise from the replacement of these ducts by infiltrating basaloid cells.3,19,20
Normally, the entire lesion is located superficially above the level of the epidermal plane with a well-demarcated lower border.4,13 Rarely, FEP will develop into a more invasive BCC.3 FEP lesions often combine features of an intracanalicular fibroadenoma of the breast, the reticulated type of seborrheic keratosis, and a superficial basal cell carcinoma.4,13 While many FEP lesions bear a strong histological resemblance to reticulated seborrheic keratosis, FEP lesions lack the typical horn and pseudohorn pearls of seborrheic keratosis.6 Recent case reports described FEP with giant cells21 and a pigmented variant of FEP.12
Special stains have been used in an attempt to classify FEP as a benign or malignant entity. Katona et al22 demonstrated that androgen receptor expression is frequently present in BCC and FEP as compared to benign follicular tumors. These data support the designation of FEP as a variant of BCC.22 However, cytokeratin 20 (CK20), which stains Merkel cells, also has been used to differentiate between BCC and benign follicular tumors.10,23
Su reports a case of a patient with two separate lesions, one a histologically confirmed FEP and the other a BCC. The FEP stained Merkel cell positive (CK20+) while the BCC stained CK20 negative, suggesting that FEP should not be considered a variant of BCC.23
Despite the availability of these special stains, debate continues regarding the benign or malignant classification of FEP.
Differential Diagnoses
While clinical examination may lead to suspected FEP, definite diagnosis requires a biopsy and subsequent histopathological examination.13 Clinical lesions must be differentiated from the following: benign fibroma, seborrheic keratosis, fibroepithelial polyp (acrochordon), amelanotic malignant melanoma, and BCC.13,23
Treatment
The treatment of choice for FEP is complete excision.13 Approaches for removal are similar to other forms of basal cell carcinoma and are case dependent.6 Lesions may be removed by Mohs micrographic surgery (MMS), standard surgical excision, destruction by various modalities, or topical chemotherapy.9
MMS is the treatment of choice for high-risk primary BCC or any recurrent BCC.9 As compared to standard surgical excision, MMS permits maximal conservation of healthy tissue.9 The fibrous stroma portion of FEP makes curettage and cautery more difficult, thus excision is preferred.13 Rarely, intralesional or topical chemotherapy (such as 5-fluorouracil) may be therapeutic.6 Radiation therapy may be considered for patients with FEP who have never received this treatment in the past.13
Prevention
Following the diagnosis and removal of FEP, or any other BCC, patients should be educated regarding the use of sunscreens with a sun protective factor of at least 15, encouraged to avoid peak intensity hours of sun exposure (10 a.m. to 3 p.m.), taught the dangers of artificial tanning, and monitored with close follow-up (at least yearly) by their dermatologists.6
A Good Prognosis
Despite the controversy mentioned earlier, patients with FEP are considered to have a rare subtype of BCC, and with proper diagnosis and treatment, have a good prognosis.9
Further research is required to document the accuracy of dermatoscopy or other more sophisticated diagnostic tools in aiding the clinical diagnosis of FEP.
Our patient had his lesion excised with a thin margin and had no recurrence 1 year later. We recommend continued yearly full-body skin examinations for our patient as well as lifelong sun protection.
PATIENT PRESENTATION
A 71-year-old man presented with this slowly growing soft nodule on his abdomen. He denied any history of skin diseases and family history was unremarkable. On physical examination there was a 1-cm x 1-cm pedunculated nodule with pinpoint hemorrhage on his abdomen. A faint area of hyperpigmentation was also present at its base. The biopsy revealed long, thin, branching strands of cells embedded within a fibrous stroma. Next to some of these strands there were small groups of dark-staining cells in a palisading pattern in the peripheral cell layer.
What is Your Diagnosis?
Diagnosis:
Fibroepithelioma of Pinkus
Despite the debate about its true nature, fibroepithelioma of Pinkus (FEP) is considered a rare variant of basal cell carcinoma (BCC) with an approximate frequency of 0.3% to 1.4%.1,2 FEP most commonly appears on the trunk or thigh,3 unlike the majority of BCCs, which occur on sun-exposed areas such as the face.4 Females have a slightly higher prevalence for FEP as opposed to most BCCs, which occur more frequently in males.5 Similar to other BCCs, this tumor develops most commonly in individuals aged 40 to 60 years old.6
FEP: Benign or Malignant?
In 1953 Herman Pinkus1 made the first description of FEP, calling it a “premalignant fibroepithelial tumor of the skin.” Recently, authors have debated whether this lesion is benign or malignant.5,7 Bowen and Leboit5 conducted a study that concludes FEP is more similar to trichoblastoma, a benign neoplasm with primitive hair follicle differentiation,8 than to BCC, a malignant neoplasm derived from nonkeratinizing cells that originate in the basal layer of the epidermis.9 Their work supports previous studies by Schulz and Hartschuh10 that suggest FEP is closer to benign trichoblastoma due to the occurrence of Merkel cells that appear in FEP as well as in trichoblastoma.11
On the other hand, the authors Ackerman and Gottlieb argue that FEP is not benign or premalignant, but rather a malignant neoplasm derived from trichoblasts, or a trichoblastic (basal cell) carcinoma.7 Controversy regarding FEP as a benign or malignant lesion continues today.
Clinical Features
Individuals present with a sessile, firm, flesh-to-pink-to-red or reddish-brown colored nodule or plaque, usually on their abdomen or thigh.12,13 Patients may have single or multiple lesions9 that clinically resemble a fibroepithelial polyp3 or a broad-based fibroma.13 Cases of FEP have been reported in other areas of the body, including on the sole of the foot,14 penis,15 thorax,16 anus, scrotum,6 and overlying breast skin.17 The development of FEP is higher in areas of previous radiation therapy.6,13 Most FEPs are asymptomatic16 with slow progression.13
Recently Zalaudek et al18 discussed a retrospective case evaluation of 10 FEPs in which they used dermatoscopy to help evaluate the lesions after histological diagnosis. The authors identified what they termed “fine arborizing vessels” in all 10 FEPs.18 These vessels of FEP are smaller in caliber and have less evident ramifications as compared to typical arborizing telangiectasias of BCCs.18 Another key dermatoscopic finding was the presence of white streaks; these were found in nine out of 10 lesions.18 While the authors identified similar features in their case study, they acknowledged the small size of their study and noted that most FEPs are not suspected clinically.
Histology
The histological appearance of FEP is characterized by long, thin, anastomosing branching strands of interwoven basaloid cells that are embedded in a fibrous stroma.1,4,9,13 Many of the strands connect with the surface epidermis.4,13 Two cell types make up the strands: one, a light-staining cell that comprises the majority of cells the other, a dark-staining cell found in scattered small groups alongside the strands with a palisading arrangement of the peripheral cell layer.4,6,13 In some cases, eccrine ducts are found within the strands of basaloid cells, leading to the speculation that FEP may arise from the replacement of these ducts by infiltrating basaloid cells.3,19,20
Normally, the entire lesion is located superficially above the level of the epidermal plane with a well-demarcated lower border.4,13 Rarely, FEP will develop into a more invasive BCC.3 FEP lesions often combine features of an intracanalicular fibroadenoma of the breast, the reticulated type of seborrheic keratosis, and a superficial basal cell carcinoma.4,13 While many FEP lesions bear a strong histological resemblance to reticulated seborrheic keratosis, FEP lesions lack the typical horn and pseudohorn pearls of seborrheic keratosis.6 Recent case reports described FEP with giant cells21 and a pigmented variant of FEP.12
Special stains have been used in an attempt to classify FEP as a benign or malignant entity. Katona et al22 demonstrated that androgen receptor expression is frequently present in BCC and FEP as compared to benign follicular tumors. These data support the designation of FEP as a variant of BCC.22 However, cytokeratin 20 (CK20), which stains Merkel cells, also has been used to differentiate between BCC and benign follicular tumors.10,23
Su reports a case of a patient with two separate lesions, one a histologically confirmed FEP and the other a BCC. The FEP stained Merkel cell positive (CK20+) while the BCC stained CK20 negative, suggesting that FEP should not be considered a variant of BCC.23
Despite the availability of these special stains, debate continues regarding the benign or malignant classification of FEP.
Differential Diagnoses
While clinical examination may lead to suspected FEP, definite diagnosis requires a biopsy and subsequent histopathological examination.13 Clinical lesions must be differentiated from the following: benign fibroma, seborrheic keratosis, fibroepithelial polyp (acrochordon), amelanotic malignant melanoma, and BCC.13,23
Treatment
The treatment of choice for FEP is complete excision.13 Approaches for removal are similar to other forms of basal cell carcinoma and are case dependent.6 Lesions may be removed by Mohs micrographic surgery (MMS), standard surgical excision, destruction by various modalities, or topical chemotherapy.9
MMS is the treatment of choice for high-risk primary BCC or any recurrent BCC.9 As compared to standard surgical excision, MMS permits maximal conservation of healthy tissue.9 The fibrous stroma portion of FEP makes curettage and cautery more difficult, thus excision is preferred.13 Rarely, intralesional or topical chemotherapy (such as 5-fluorouracil) may be therapeutic.6 Radiation therapy may be considered for patients with FEP who have never received this treatment in the past.13
Prevention
Following the diagnosis and removal of FEP, or any other BCC, patients should be educated regarding the use of sunscreens with a sun protective factor of at least 15, encouraged to avoid peak intensity hours of sun exposure (10 a.m. to 3 p.m.), taught the dangers of artificial tanning, and monitored with close follow-up (at least yearly) by their dermatologists.6
A Good Prognosis
Despite the controversy mentioned earlier, patients with FEP are considered to have a rare subtype of BCC, and with proper diagnosis and treatment, have a good prognosis.9
Further research is required to document the accuracy of dermatoscopy or other more sophisticated diagnostic tools in aiding the clinical diagnosis of FEP.
Our patient had his lesion excised with a thin margin and had no recurrence 1 year later. We recommend continued yearly full-body skin examinations for our patient as well as lifelong sun protection.
