Folliculo‐sebaceous cystic hamartoma
Authors: El‐Darouty Mohammad A. , Marzouk Salonas A. , Abdel‐Halim Mona R. E. , El‐Komy Mohammad H. M. , Mashaly Heba M. 
Published: March 2003

Case 1 A 6‐month‐old boy presented to our clinic with a scalp lesion dating since birth (Fig. 1). The lesion was in the form of an erythematous, dome‐shaped nodule, measuring around 1.5 cm in diameter and having a slightly irregular surface. The lesion was nonitchy, nontender, and showed limited mobility. Our clinical differential diagnosis included: meningocele, hemangioma, dermoid cyst, and apocrine nevus. A computed tomography (CT) scan was performed to exclude possible intracranial connection, and the lesion was surgically excised.

Case 1: erythematous nodule on the occipital area of a 6‐month‐old boy. The lesion was clinically suggestive of apocrine nevus, dermoid cyst, or meningocele

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Histopathologic examination (Fig. 2) revealed a markedly dilated follicular cystic structure, with numerous sebaceous lobules arising from its wall. Other cystic structures containing keratin, but no hair, were also seen. There were numerous sebaceous lobules, excess fibrous tissue (showing a lamellar pattern around the cystic structures and sebaceous lobules), and excess fatty tissue, but no muscles of hair erection were found in the lesion. Clefts were seen separating the pericystic fibrous tissue from the rest of the dermis. Collections of blood vessels were detected in the lower part of the lesion. These features are characteristic and seen only in folliculo‐sebaceous cystic hamartoma.

large infundibular cystic structure with numerous sebaceous lobules and rudimentary follicles arising from its wall. Individual sebaceous lobules are seen surrounding the cyst. Lamellar fibrous tissue is seen around the cyst and separated from the surrounding stroma by clear clefts. Numerous blood vessels, muscle fibers, and adipose tissue are seen in the lower part (× 100)

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Case 2 A 55‐year‐old woman presented with two erythematous, dome‐shaped nodules on the scalp of more than 10 years' duration (Fig. 3). Each lesion measured about 1 cm in diameter, exhibited soft consistency, and showed limited mobility. Apart from the unsightly appearance, the lesions were symptomless. The clinical differential diagnosis included: intradermal nevus, apocrine nevus, nevus sebaceous, and syringocystadenoma papilliferum.

Case 2: skin‐colored nodules on the back of the scalp of a 55‐year‐old woman

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Microscopic examination (Fig. 4) revealed a mid‐dermal cystic structure lined by follicular epithelium with numerous rudimentary hair follicles and sebaceous lobules arising from its wall. There were also numerous sebaceous lobules, as well as excess fibrous and fatty tissue. Clefts were seen separating the lamellar pericystic fibrous tissue from the rest of the dermis. These features are diagnostic of folliculo‐sebaceous cystic hamartoma.

Infundibular cystic structure not connected to the overlying epidermis showing the same features as in Fig. 2, with a large number of isolated sebaceous lobules. There is pericystic compact lamellar fibrous tissue separated from the surrounding stroma by clear clefts (× 100)

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