Trichoblastoma and Compound Nevus Arising from Nevus Sebaceus

Oh, Su Jin; Han, Sung Soo; Park, Hyung Kwon; Yu, Hee Joon; Kim, Joung Soo

Abstract

Nevus sebaceous is a common congenital cutaneous hamartoma occurring mainly on the face and scalp. It is well known that secondary neoplasms can be easily observed in the primary lesion. However, a case of trichoblastoma and compound nevus concurrently arising from nevus sebaceous has not been previously reported. A 26-year-old woman presented with a well-demarcated atrophic skin-colored plaque on her scalp from birth. On the plaque, a black dome-shaped round nodule and a brownish nodule with irregular margins were found one week previously without subjective symptoms. Histopathological examination of the central plaque lesion revealed epidermal hyperplasia and hyperplasia of the sebaceous glands and eccrine glands. In addition, ectopic, dilated apocrine glands were revealed in the lower dermis, and the hair follicles remained small and primordial, consistent with nevus sebaceous. A section of the black nodule showed palisading basaloid cells surrounded by abundant fibrous stroma. Nests of nevus cells were found at the dermo-epidermal junction and dermis in the brownish nodule. Based on these findings, the black nodule and brownish nodule were diagnosed as trichoblastoma and compound nevus, respectively. Herein, we report an interesting case of trichoblastoma and compound nevus concurrently arising from nevus sebaceous, which is, to our knowledge, the first such report in the dermatologic literature.