Severely atypical medium-sized congenital nevus with widespread satellitosis and placental deposits in a neonate: the problem of congenital melanoma and its simulants.

We describe a neonate with a highly atypical melanocytic proliferation that arose in a medium-sized congenital nevus, in association with multiple cutaneous satellite lesions and placental deposits. The patient's pathologic findings and benign clinical course to date raise the problem of diagnosis of congenital melanoma and the importance of clinical follow-up to determine the biologic behavior of severely atypical, histologically malignant proliferations in congenital melanocytic nevi.