2018 Volume 128 Issue 4 Pages 601-605
A 63-year-old man presented with irregular brown streaks over the entire left great toe nail plate and with Hutchinson's sign. Our initial diagnosis was melanoma in situ, and the nail was surgically removed just proximal to the distal phalanx. A pathological examination revealed solitary proliferation and nest formation of oval-shaped tumor cells on the basal layer of nail bed, expanding from the nail matrix to the toe tip. There were also increased numbers of spindle-shaped cells in the dermis, accompanied by collagen fibers. The tumor cells stained positively for S-100 and negatively for Melan-A. Some epidermal tumor cells were positive for HMB-45; dermal tumor cells were negative. Based on these findings, desmoplastic melanoma was diagnosed. Four months after surgery, the tumor cells had metastasized to the left inguinal lymph nodes, followed by metastasis to the lungs 19 months after surgery. This case is unique because the desmoplastic melanoma affected the toe nail bed, showing pigmentation and mild nail deformity.
