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The Diagnosis: Congenital Folliculosebaceous Cystic Hamartoma
Folliculosebaceous cystic hamartoma (FSCH) is a rare skin condition that is either congenital or acquired. It presents as a slow-growing and flesh-colored papulonodular lesion1 that mainly occurs on the head and neck. Involvement of the nipples, perineum, back, forearms, genital areas, and subcutaneous tissue also has been reported but usually indicates a larger lesion.1,2
Histologically, FSCH is considered a hamartoma composed of both ectodermal and mesodermal elements.1 Folliculosebaceous cystic hamartoma is a more complex lesion composed of infundibulocystic structures connected to maloriented folliculosebaceous units surrounded by whorls of highly vascularized fibrous stroma and adipocytes. Clefts between fibroepithelial units and surrounding stroma usually are present.1
Epithelial components contribute to the adnexal and folliculosebaceous cystic proliferations, and mesenchymal elements include vascular tissue, adipose tissue, and fibroblast-rich stroma.1,2 Acquired lesions arising in adults have been described,1-5 but the congenital presentation of FSCH in infancy is rare.
Histopathologically, some variations of FSCH are mainly composed of epithelial components while others are composed of nonepithelial components. Nonepithelial components include neural proliferation, muscle components, vascular proliferation, and mucin deposition.1-4 In some cases, FSCH may coexist with other diseases, such as nevus lipomatosus cutaneous superficialis and neurofibromatosis type I.4,5
In our case, histopathology showed several dermal infundibulocystic structures that were lined by stratified squamous epithelium and contained horny material (Figure 1). Numerous immature sebaceous lobules and rudimentary hair follicles emanated from some of the cyst walls. Mesenchymal changes around the fibroepithelial units included fibrillary bundles of collagen, clusters of adipocytes, and an increased number of small venules (Figure 2). In addition, the stroma adjacent to the malformed perifollicle contained some amount of mucin. Prominent clefts formed between fibroepithelial units and the surrounding altered stroma.
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The differential diagnosis mainly includes sebaceous trichofolliculoma, molluscum contagiosum, dermoid cysts, pilomatrixoma, Spitz nevus, and nevus lipomatosus superficialis. The differential diagnosis between FSCH and sebaceous trichofolliculoma is challenging. Both lesions show an infundibular cyst and surrounding sebaceous nodules. According to Plewig,6 trichofolliculoma has a wide spectrum ranging from low to high differentiation represented by trichofolliculoma, sebaceous trichofolliculoma, and FSCH, respectively. It is not difficult to distinguish FSCH from other diseases according to its peculiar histopathologic features.
The clinicopathologic features of our case were similar to those of reported FSCH cases, except for the following unique characteristics: congenital lesion, lack of terminal hair, and no sebaceous material extrusion. These features of hair and sebaceous material may be correlated with the patient’s age and hormonal level.1 Androgen may play a key role in sebaceous gland development at puberty, which leads to sebaceous gland hyperplasia and hypertrophy. Therefore, slight pressure from the lesions can make ivory-white sebaceous material discharge. Hence, the dermatologist and pediatrician must be poised and sensitive while making an initial diagnosis of FSCH.
1. Kimura T, Miyazawa H, Aoyagi T, et al. Folliculosebaceous cystic hamartoma: a distinctive malformation of the skin. Am J Dermatopathol. 1991;13:213-220.
2. Moriki M, Ito T, Hirakawa S, et al. Folliculosebaceous cystic hamartoma presenting as a subcutaneous nodule on the thigh. J Dermatol. 2013;40:483-484.
3. Aloi F, Tomasini C, Pippione M. Folliculosebaceous cystic hamartoma with perifollicular mucinosis. Am J Dermatopathol. 1996;18:58-62.
4. Brasanac D, Boricic I. Giant nevus lipomatosus superficialis with multiple folliculosebaceous cystic hamartomas and dermoid cysts. J Eur Acad Dermatol Venereol. 2005;19:84-86.
5. Noh S, Kwon JE, Lee KG, et al. Folliculosebaceous cystic hamartoma in a patient with neurofibromatosis type I. Ann Dermatol. 2011;23(suppl 2):S185-S187.
6. Plewig G. In discussion of: Leserbrief zu Zheng LQ, Han XC, Huang Y, Li HW. Several acneiform papules and nodules on the neck. diagnosis: folliculosebaceous cystic hamartoma. J Dtsch Dermatol Ges. 2014;12:824-825.
The Diagnosis: Congenital Folliculosebaceous Cystic Hamartoma
Folliculosebaceous cystic hamartoma (FSCH) is a rare skin condition that is either congenital or acquired. It presents as a slow-growing and flesh-colored papulonodular lesion1 that mainly occurs on the head and neck. Involvement of the nipples, perineum, back, forearms, genital areas, and subcutaneous tissue also has been reported but usually indicates a larger lesion.1,2
Histologically, FSCH is considered a hamartoma composed of both ectodermal and mesodermal elements.1 Folliculosebaceous cystic hamartoma is a more complex lesion composed of infundibulocystic structures connected to maloriented folliculosebaceous units surrounded by whorls of highly vascularized fibrous stroma and adipocytes. Clefts between fibroepithelial units and surrounding stroma usually are present.1
Epithelial components contribute to the adnexal and folliculosebaceous cystic proliferations, and mesenchymal elements include vascular tissue, adipose tissue, and fibroblast-rich stroma.1,2 Acquired lesions arising in adults have been described,1-5 but the congenital presentation of FSCH in infancy is rare.
Histopathologically, some variations of FSCH are mainly composed of epithelial components while others are composed of nonepithelial components. Nonepithelial components include neural proliferation, muscle components, vascular proliferation, and mucin deposition.1-4 In some cases, FSCH may coexist with other diseases, such as nevus lipomatosus cutaneous superficialis and neurofibromatosis type I.4,5
In our case, histopathology showed several dermal infundibulocystic structures that were lined by stratified squamous epithelium and contained horny material (Figure 1). Numerous immature sebaceous lobules and rudimentary hair follicles emanated from some of the cyst walls. Mesenchymal changes around the fibroepithelial units included fibrillary bundles of collagen, clusters of adipocytes, and an increased number of small venules (Figure 2). In addition, the stroma adjacent to the malformed perifollicle contained some amount of mucin. Prominent clefts formed between fibroepithelial units and the surrounding altered stroma.
| | |
|
The differential diagnosis mainly includes sebaceous trichofolliculoma, molluscum contagiosum, dermoid cysts, pilomatrixoma, Spitz nevus, and nevus lipomatosus superficialis. The differential diagnosis between FSCH and sebaceous trichofolliculoma is challenging. Both lesions show an infundibular cyst and surrounding sebaceous nodules. According to Plewig,6 trichofolliculoma has a wide spectrum ranging from low to high differentiation represented by trichofolliculoma, sebaceous trichofolliculoma, and FSCH, respectively. It is not difficult to distinguish FSCH from other diseases according to its peculiar histopathologic features.
The clinicopathologic features of our case were similar to those of reported FSCH cases, except for the following unique characteristics: congenital lesion, lack of terminal hair, and no sebaceous material extrusion. These features of hair and sebaceous material may be correlated with the patient’s age and hormonal level.1 Androgen may play a key role in sebaceous gland development at puberty, which leads to sebaceous gland hyperplasia and hypertrophy. Therefore, slight pressure from the lesions can make ivory-white sebaceous material discharge. Hence, the dermatologist and pediatrician must be poised and sensitive while making an initial diagnosis of FSCH.
The Diagnosis: Congenital Folliculosebaceous Cystic Hamartoma
Folliculosebaceous cystic hamartoma (FSCH) is a rare skin condition that is either congenital or acquired. It presents as a slow-growing and flesh-colored papulonodular lesion1 that mainly occurs on the head and neck. Involvement of the nipples, perineum, back, forearms, genital areas, and subcutaneous tissue also has been reported but usually indicates a larger lesion.1,2
Histologically, FSCH is considered a hamartoma composed of both ectodermal and mesodermal elements.1 Folliculosebaceous cystic hamartoma is a more complex lesion composed of infundibulocystic structures connected to maloriented folliculosebaceous units surrounded by whorls of highly vascularized fibrous stroma and adipocytes. Clefts between fibroepithelial units and surrounding stroma usually are present.1
Epithelial components contribute to the adnexal and folliculosebaceous cystic proliferations, and mesenchymal elements include vascular tissue, adipose tissue, and fibroblast-rich stroma.1,2 Acquired lesions arising in adults have been described,1-5 but the congenital presentation of FSCH in infancy is rare.
Histopathologically, some variations of FSCH are mainly composed of epithelial components while others are composed of nonepithelial components. Nonepithelial components include neural proliferation, muscle components, vascular proliferation, and mucin deposition.1-4 In some cases, FSCH may coexist with other diseases, such as nevus lipomatosus cutaneous superficialis and neurofibromatosis type I.4,5
In our case, histopathology showed several dermal infundibulocystic structures that were lined by stratified squamous epithelium and contained horny material (Figure 1). Numerous immature sebaceous lobules and rudimentary hair follicles emanated from some of the cyst walls. Mesenchymal changes around the fibroepithelial units included fibrillary bundles of collagen, clusters of adipocytes, and an increased number of small venules (Figure 2). In addition, the stroma adjacent to the malformed perifollicle contained some amount of mucin. Prominent clefts formed between fibroepithelial units and the surrounding altered stroma.
| | |
|
The differential diagnosis mainly includes sebaceous trichofolliculoma, molluscum contagiosum, dermoid cysts, pilomatrixoma, Spitz nevus, and nevus lipomatosus superficialis. The differential diagnosis between FSCH and sebaceous trichofolliculoma is challenging. Both lesions show an infundibular cyst and surrounding sebaceous nodules. According to Plewig,6 trichofolliculoma has a wide spectrum ranging from low to high differentiation represented by trichofolliculoma, sebaceous trichofolliculoma, and FSCH, respectively. It is not difficult to distinguish FSCH from other diseases according to its peculiar histopathologic features.
The clinicopathologic features of our case were similar to those of reported FSCH cases, except for the following unique characteristics: congenital lesion, lack of terminal hair, and no sebaceous material extrusion. These features of hair and sebaceous material may be correlated with the patient’s age and hormonal level.1 Androgen may play a key role in sebaceous gland development at puberty, which leads to sebaceous gland hyperplasia and hypertrophy. Therefore, slight pressure from the lesions can make ivory-white sebaceous material discharge. Hence, the dermatologist and pediatrician must be poised and sensitive while making an initial diagnosis of FSCH.
1. Kimura T, Miyazawa H, Aoyagi T, et al. Folliculosebaceous cystic hamartoma: a distinctive malformation of the skin. Am J Dermatopathol. 1991;13:213-220.
2. Moriki M, Ito T, Hirakawa S, et al. Folliculosebaceous cystic hamartoma presenting as a subcutaneous nodule on the thigh. J Dermatol. 2013;40:483-484.
3. Aloi F, Tomasini C, Pippione M. Folliculosebaceous cystic hamartoma with perifollicular mucinosis. Am J Dermatopathol. 1996;18:58-62.
4. Brasanac D, Boricic I. Giant nevus lipomatosus superficialis with multiple folliculosebaceous cystic hamartomas and dermoid cysts. J Eur Acad Dermatol Venereol. 2005;19:84-86.
5. Noh S, Kwon JE, Lee KG, et al. Folliculosebaceous cystic hamartoma in a patient with neurofibromatosis type I. Ann Dermatol. 2011;23(suppl 2):S185-S187.
6. Plewig G. In discussion of: Leserbrief zu Zheng LQ, Han XC, Huang Y, Li HW. Several acneiform papules and nodules on the neck. diagnosis: folliculosebaceous cystic hamartoma. J Dtsch Dermatol Ges. 2014;12:824-825.
1. Kimura T, Miyazawa H, Aoyagi T, et al. Folliculosebaceous cystic hamartoma: a distinctive malformation of the skin. Am J Dermatopathol. 1991;13:213-220.
2. Moriki M, Ito T, Hirakawa S, et al. Folliculosebaceous cystic hamartoma presenting as a subcutaneous nodule on the thigh. J Dermatol. 2013;40:483-484.
3. Aloi F, Tomasini C, Pippione M. Folliculosebaceous cystic hamartoma with perifollicular mucinosis. Am J Dermatopathol. 1996;18:58-62.
4. Brasanac D, Boricic I. Giant nevus lipomatosus superficialis with multiple folliculosebaceous cystic hamartomas and dermoid cysts. J Eur Acad Dermatol Venereol. 2005;19:84-86.
5. Noh S, Kwon JE, Lee KG, et al. Folliculosebaceous cystic hamartoma in a patient with neurofibromatosis type I. Ann Dermatol. 2011;23(suppl 2):S185-S187.
6. Plewig G. In discussion of: Leserbrief zu Zheng LQ, Han XC, Huang Y, Li HW. Several acneiform papules and nodules on the neck. diagnosis: folliculosebaceous cystic hamartoma. J Dtsch Dermatol Ges. 2014;12:824-825.
A 3-year-old girl was referred to our clinic for a lesion on the face that had been present since birth and had enlarged slowly with slight itching. Physical examination revealed a 1.0×1.0-cm, sessile, flesh-colored, sharply demarcated, and dome-shaped papule with a bloody crust. It was firm and slightly painful to palpation. Dilated hair follicle–like orifices and thick central terminal hair were not found. Sebaceous material was not discharged. There was no notable family history or evidence of systemic disease. The lesion was surgically removed for cosmetic reasons and further histopathologic examination was performed.
