Letter to the Editor
Basaloid follicular hamartoma on the upper eyelid

Basaloid follicular hamartoma (BFH) is a benign rare neoplasm of the hair follicles whose clinical and histological appearance is very similar to basal cell carcinoma. Although these hamartomas are considered to be benign lesions, malignant differentiations have been reported. It may be generalized or localized, familial or sporadic, and BFH can be accompanied by systemic diseases. Although there are many clinical forms of BFH, they all have the same histopathological features. Basaloid follicular hamartoma is a folliculocentric tumor limited to the superficial dermis. Involvement of the deep reticular dermis or soft tissue is not seen in BFH [1].
We present a 52-year-old man with a solitary, hyperpigmented, asymptomatic, slow growing skin tumor on his left upper eyelid.
A 52-year-old man presented with a slowly developing asymptomatic left upper eyelid lesion (over 4 years). Dermatological examination showed a solitary, smooth surfaced, hyperpigmented nodule measuring 1 cm in diameter (Figure 1), and there were no other similar skin lesions or significant internal diseases exhibited. He had no family history of similar lesions. The lesion was locally excised, and the specimen was grossly measured to be 1.2 × 0.7 × 0.2 cm.
Low-power light microscopy revealed a well-circumscribed and completely removed lesion in the dermis, without connections to the epidermis (Figure 2). Microscopically, the tumor revealed strands and cords of small basaloid cells emanating from the infundibular portion of the hair follicle. The tumor stroma was scant and mildly fibrocellular. There was no nuclear pleomorphism, mitotic activity, apoptotic cells, or cleft formation between the tumor and the stroma (Figure 3), and upon immunohistochemical examination, Bcl-2 stained only in the outermost basal cells (Figure 4). Cd34 was positively stained in the peritumoral stroma and blood vessels (Figure 5), and CD10 was stained in the peritumoral stroma as well as the matrical cells (Figure 6).
Basaloid follicular hamartoma was first described in 1969 by Brown et al. as “generalized hair follicle hamartoma” with associated alopecia, aminoaciduria, and myasthenia gravis [2]. The term “basaloid follicular hamartoma” was first used for a patient who had a localized and solitary type of the lesion, without associated abnormalities, by Mehregan and Baker in 1985 [3]. Morohashi et al. described BFH as an abortive growth of secondary hair germs with a limited...


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