Pigmented Trichogerminoma: A Case Report

ABSTRACT

Trichogerminoma is a rare cutaneous adnexal tumor that dysplays differentiation toward the hair germ epithelium. This tumor was first described by Sau et al. in 1992 and it is characterized by densely packed round nests or cell balls resembling hair bulbs. Herein, we report on a deeply pigmented and sharply circumscribed nodular tumor that was excised on the abdomen of a 48-year-old woman. Histologically the tumor involved both dermis and subcutis without any epidermal connection. The main nodule was subdivided into the smaller lobules by fibrous stroma. The lobules were composed of masses of basaloid cells that displayed peripheral palisading. Within the lobules, the basaloid cells formed numerous cell balls. The tumor presented the characteristic features of trichogerminoma. Interestingly, our case was the pigmented type, which was remarkable by virtue of the heavy melanin deposits found within and around the tumor nests. To the best of our knowledge, this is the first case of pigmented trichogerminoma that has been reported worldwide.