Cutaneous inflammation as a marker of malignant transformation in a patient with linear unilateral basaloid follicular hamartoma.

Basaloid follicular hamartoma is a rare, benign and superficial malformation of hair follicles, characterized histologically by epithelial proliferation of basaloid cells with radial disposition. It can be mistaken for basal cell carcinoma. Even though these hamartomas are considered benign lesions, malignant transformation has rarely been reported. We report the case of a 45-year-old healthy woman, with linear, unilateral basaloid follicular hamartoma which developed inflamed papules histologically suggestive of basal cell carcinoma. We believe that identification of local inflammation could be a clinical clue to guide us towards a malignant transformation of basaloid follicular hamartoma.

Clinicopathologic analysis of 21 cases of nevus sebaceus: a retrospective study.

BACKGROUND: Nevus sebaceus (NS), otherwise designated as 'organoid nevus', involves proliferative changes of the sebaceous glands, sweat glands, and the hair follicles. It displays a range of appearances, depending on the lesion's age. AIMS: To study the histopathological features of NS and correlate these with clinical findings. METHODS: All skin biopsy specimens over a 12-year period from 1995 to 2007 which had a diagnosis of NS were included. Clinical data with follow-up notes and histopathology were reviewed. RESULTS: Half of the cases had a verrucous clinical appearance, while the rest presented as papules, plaques, or patches. All the cases showed immature hair follicles, and 24% of cases showed immature sebaceous glands. Normal terminal hair follicles were characteristically absent in the lesion. Nineteen percent of the cases showed dilated apocrine glands, and 14% showed hyperplasia of eccrine glands. Epidermal changes in the form of acanthosis, papillomatosis, and hyperkeratosis were seen in 86% of cases. Dilated keratin-filled infundibula were observed in 24% of cases. One case was associated with a squamous cell carcinoma. CONCLUSIONS: Nevus sebaceus is a cutaneous hamartoma, consisting of various elements indigenous to the organ. Normal terminal hair follicles are characteristically absent in the lesion although the same may be seen in rest of the epidermis, a feature of diagnostic importance, not usually highlighted in literature. The divergent differentiation observed in NS is consistent with the common embryologic origin of the folliculosebaceous-apocrine unit and should not mislead the pathologist.