Congenital Giant Folliculosebaceous Cystic Hamartoma of Thigh: A Rare Case.

Hamartomatous conditions of skin are comprised of variable composition of normal skin elements. They can present as nodular masses. They can be mistaken for neoplastic skin lesions. Folliculosebaceous cystic hamartoma is a rare skin condition seen in adults, commonly on head, neck and face region. Congenital variant is rare. Only few case reports have been described in literature occurring on sites other than face. Definitive diagnosis can be given only on histopathology. We report a case presenting as thigh mass in a 1 year old female child clinically diagnosed as papilloma of skin. Copyright:

Introduction

Folliculosebaceous cystic hamartoma (FSCH) was first described in 1991 by Kimura et al.[1] Clinically, they are confused with various benign tumors of the skin. FSCH usually presents as solitary, 0.5–1.5 cm, flesh-colored, sessile or pedunculated mass, usually on the head, especially on the central part of the face and nose.[23] Literature described very few cases of giant FSCH occurring on areas other than the face.[45] There are only a few case reports described in infants and occurring congenitally.[6]

Case Report

An 1-year-old female child presented with posterior thigh mass since birth, gradually increasing in size to the present size of 10 cm × 8 cm × 5 cm [Figure 1]. The mass was polypoidal, soft to firm in consistency, fixed to the skin. The surface was covered with skin with multiple lobulations showing scattered dilated pores with a thick oily discharge. Clinical diagnosis of sessile papilloma of the skin was given following which wide local excision was performed. The excised lesion was a polypoidal mass of the size 10 cm x 8 cm x 6 cm. Cut surface showed fleshy pinkish-white tissue with multiple cysts filled with whitish-yellow material [Figure 2].

Figure 1

A sessile mass on posterior aspect of thigh with multiple small openings on the surface

Figure 2

Cut surface showing multiple cystic spaces with yellowish material. Inset showing external polypoidal surface of FSCH

Histopathology showed hyperkeratotic acanthotic epidermis. Dermis showed multiple dilated pilosebaceous units containing infundibular type keratinization with numerous sebaceous lobules radiating from it. These cystic follicular structures were surrounded by mesenchymal tissue with some increase in muscle component near the sebaceous lobules. No secondary hair follicles were seen. The folliculocystic structures were wrapped in densely laminated collagen bundles and abundant adipose tissue with vascular proliferation [Figures 3 and 4].

Figure 3

Dilated pilosebaceous unit with radiating sebaceous lobules (H and E, ×100)

Figure 4

Increased mesenchymal tissue surrounding dilated pilosebaceous units (H and E, ×100)

Discussion

FSCH is an uncommon skin lesion presenting as nodular mass. It is considered as hamartoma because of multiple mature ectodermal and mesodermal elements. The most common location in adults is the middle part of the face as described. Merklen-Djafri et al. studied 25 cases of FSCH over a period of 25 years with a mean age of 51 year, occurring commonly on the face.[7] Giant variants have been described on other parts of the body. It is rarely seen in children below 1 year. Similar clinical presentation as our case was described by Emsen and Livaoglu, where it was considered as congenital form.[6] Nomura and Hata described the rare site of scrotum in a 22-year-old male patient.[8] Our patient had a mass since birth which had increased to the present size in 1 year. The clinical diagnosis in all previously reported cases was given as papilloma, intradermal nevi, sebaceous hyperplasia, lipomas, dermoid cysts, and neurofibromas but not FSCH. Histologically, a differential diagnosis of sebaceous trichofolliculoma was considered initially but was ruled out due to the absence of multiple refractile vellus hair shafts. Furthermore, the characteristic mesenchymal stroma is absent in sebaceous trichofolliculoma. Donati and Balus described the proliferation of the nerve fibers along with other mesenchymal elements.[9] Noh et al. described the FSCH occurring in a patient of neurofibromatosis which was misdiagnosed as neurofibroma clinically on left earlobe.[10]

Conclusion

FSCH is a rare skin lesion always misdiagnosed as other benign skin lesions and it can only be categorized correctly as hamartoma on histology. Although very rare, it should be kept in mind while diagnosing congenital skin lesions. Our case is probably the second case of giant FSCH of congenital origin.

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Conflicts of interest

There are no conflicts of interest.