A Case of Epidermotropic Metastatic Malignant Melanoma with Multiple Nodular Lesions of the Scalp

Abstract

Epidermotropic metastatic malignant melanoma (EMMM) is a form of metastatic malignant melanoma that has dermal cell nests with epidermotropism and specific histopathological features. We report a patient with eight nodular lesions of the scalp with histopathological findings compatible with EMMM. The tumors developed one year before consultation and increased in size simultaneously. The histopathological findings of all eight tumors were very similar. The tumor cells were located mainly in the dermis and partly in the basal layer of the epidermis. They contained melanin pigments and were positive for anti-HMB45 antibody. The tumors did not respond to combination chemotherapy with dacarbazine, nimustine, vincristine, and interferon-beta. Therefore, all the tumors were surgically removed. No local relapse, distant metastasis or re-elevation of plasma 5-S-cysteinyldopa was identified during nine months of follow-up. Histopathologically, all eight tumors lacked apparent vascular invasion, which may be related to a slow clinical course of the present case.