Hybrid eccrine gland and hair follicle hamartoma: a new entity of adnexal nevus.

Eccrine nevus shows increase in number or size of eccrine glands, whereas hair follicle nevus is composed of densely packed normal vellus hairs, and eccrine-pilar angiomatous nevus reveals increase of eccrine, pilar, and angiomatous structures. No case with increased number of both eccrine glands and hair follicles only in the dermis has been previously reported. A 10-month-old girl presented with cutaneous hamartoma with overlying skin hyperpigmentation on her left hypochondrium since 3 months of age, in whom the lesion was completely excised. Histopathology demonstrated evidently increased number of both eccrine glands and hair follicles in the dermis with reactive hyperplasia of collagen fibers. No recurrence occurred after the tumor was completely excised. A term "hybrid eccrine gland and hair follicle hamartoma" is proposed for this unique lesion.