Malignant blue nevus with neurosarcoma-like lymph node metastases

We report a case of malignant blue nevus (MBN) of the foot with unusual morphologic presentation of nodal metastases. Their structure resembled neurosarcoma, and differed from the appearance of the primary tumor. This case confirms the mutual close histogenic relationship between MBN and neurosarcoma, both tumors originating from the structures of the neural crest. We also discuss the problem of so-called "benign" metastases of malignant melanoma.