A 63-year-old Japanese woman was referred to us with a 1-month history of a nodule arising within a lesion of medium-sized congenital melanocytic nevus of the left popliteal region. Physical examination showed a black plaque, 13.6×7.7cm, on the site, and at the periphery of which, a reddish black nodule, 1.8×1.4×0.5cm, was detected.
Histopathological examination of the nodule revealed nests of atypical melanocytes in the upper dermis. The overlying epidermis was eroded and no proliferation of atypical melanocytes was found in the epidermis. The plaque lesion histologically showed diffuse proliferation of small nevus cells in the reticular dermis. The border between the atypical melanocytes and the nevus cells was somewhat indistinct. The atypical cells were epithelioid or spindle shaped, and mitotic figures were frequently detected. The atypical cells were stained with an antibody to S-100 protein and some of them were also stained with a HMB-45.
This case is malignant melanoma arising from a medium-sized congenital melanocytic nevus. The stage was pT4a N2a M1a (Stage IV).
She underwent wide local resection along with subtotal integumentectomy and radical lymph node dissection of her left inguinal area. DAV-feron (DTIC, ACNU, VCR, IFN-β) therapy was administered postoperatively. However, soon later, metastases to lung, bones, and brain developed. She died from the disease on July 9, 1999.
