Pigmented trichoblastoma arising from the nevus sebaceous: a rare case in Korea.

Trichoblastoma is occasionally observed in association with a pre-existing nevus sebaceous in the Korean literature. However, there has been no report on the pigmented type. Herein, we report the first Korean case of a pigmented trichoblastoma arising from the nevus sebaceous on the forehead. A 28-year-old male presented with a dark nodular lesion within a yellowish plaque on the forehead. The surrounding yellowish plaque on the forehead had existed since birth. The central, dark-pigmented nodule began to appear three years ago and enlarged gradually. Histopathologic findings of central pigmented lesion showed heavy melanin deposits within and around the tumor nests. Complete excision was made as treatment.