HAIR FOLLICLE NEVI AND ACCESSORY TRAGI - VARIABLE QUANTITY OF ADIPOSE-TISSUE IN CONNECTIVE-TISSUE FRAMEWORK

Controversy exists about the histologic differences between hair folli cle nevi and accessory tragi, We examined 10 congenital lesions histol ogically, possible diagnoses of which were hair follicle nevi or acces sory tragi, Two specimens out of the 10 had tiny, mature hair follicle s surrounded by thick fibrous root sheaths, a few fat cells, and no ca rtilage, The subcutaneous fat cells of their bases were segmented by a connective tissue framework, They had histologic features of hair fol licle nevi, One specimen had cartilage and abundant fat cells with a c onnective tissue framework in the nodule, as well as a conglomeration of numerous well-differentiated hair follicles, It possessed both elem ents of a hair follicle nevus and an accessory tragus. Seven specimens had abundant subcutaneous fat and showed a prominent connective tissu e framework. These were typical accessory tragi, The present study sug gests that the number of fat cells in the nodule or papule differs bet ween these two conditions, All the lesions studied revealed a connecti ve tissue framework in the subcutaneous fat, Histologic features of bo th hair follicle nevi and accessory tragi can coexist in a single lesi on. Hair follicle nevi may represent incomplete accessory tragi with s cant fat cells.