CONGENITAL NEUROVASCULAR HAMARTOMA OF THE SKIN - A POSSIBLE MARKER OFMALIGNANT RHABDOID TUMOR

Distinct congenital, benign, probably hamartomatous, lesions of the up per dermis were noted in two children who subsequently developed malig nant rhabdoid tumors. The dermal lesions, which we have named ''neurov ascular hamartomas'' were characterized by a proliferation of capillar ies in a background of bland spindle cells with possible neural featur es. In one child the malignant rhabdoid tumor was located in the kidne y, and a synchronous primitive neuroectodermal tumor of the central ne rvous system was the cause of his death. The other infant had two neur ovascular hamartomas, and a malignant rhabdoid tumor arose in contigui ty with the deepest portion of the larger of the two hamartomas. An ax illary lymph node metastasis rapidly developed in this child followed by widespread metastases and death 3 months later. Neuroectodermal dif ferentiation was observed immunohistochemically or ultrastructurally i n all rhabdoid tumors and in the tumor of the brain. This is the first report of a unique congenital benign dermal lesion that appears to be associated with malignant rhabdoid tumors in very young children. A g enetic abnormality of neuroectodermal differentiation may underlie the development of these neoplasms.