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Feb 2012

A Preauricular Hairy Papule in an Infant: Hair Follicle Nevus Closely Similar to Accessory Tragus

Author Affiliations

Author Affiliations: Division of Dermatology, Department of Internal Medicine, Faculty of Medicine, Saga University, Saga, Japan (Drs Kotaro Nagase, Misago, and Narisawa); and Division of Dermatology, Nagase Dermatology Clinic, Saga (Dr Koichi Nagase).

Arch Dermatol. 2012;148(2):266-268. doi:10.1001/archdermatol.2011.2135

Accessory tragus is a fairly common congenital malformation of the external ear. However, it is extremely difficult to make a distinction between accessory tragus without cartilage and hair follicle nevus. Hair follicle nevus is an extremely rare adnexal hamartoma with follicular differentiation that commonly presents as a nodule on the face.

A 2-month-old Japanese boy presented with an elastic, soft, pedunculated, hairy, light brown papule, 3 mm in diameter, that had been on the right preauricular area since birth (Figure 1). His family history was noncontributory. The lesion was diagnosed as accessory tragus, excised, and examined histologically. Hematoxylin-eosin stains showed the crowding of many tiny mature hair follicles in different stages in the dermis (Figure 2). Several sebaceous glands connected with the hair follicle, and there was abundant fat and a few eccrine glands. Serial sections revealed no cartilage and no central dilated infundibulum, excluding the possibility of trichofolliculoma.