Congenital melanoma with multiple prenatal metastases.

A 1.95-kg fetus delivered at 33 weeks' gestational age survived less than 1 hour. Physical examination and autopsy disclosed an enormous, protuberant primary malignant melanoma of the skin, enveloping most of the back. A rim of surrounding hyperpigmented skin proved to be a giant congenital melanocytic nevus (GCMN), from which the cutaneous melanoma had arisen. Autopsy demonstrated metastatic melanoma in the lungs, liver, spinal cord, leptomeninges, and placenta. Radiography and dissection confirmed that the melanoma had minimal connection to spinal or neural structures. The mother was clinically free of tumor 8 months after she was delivered of the infant. Pathologic, radiographic, histologic, immunohistochemical, and ultrastructural investigations of this unique case are presented.