Congenital malignant rhabdoid tumor of the orbit.

Malignant rhabdoid tumor is a rare and highly malignant renal tumor of infancy. Extrarenal tumors involving the orbit have been reported, but never at birth. The authors describe a primary malignant rhabdoid tumor of the orbit in a neonate who had massive unilateral proptosis at birth. Clinical, radiographic, and histologic features of the tumor are discussed.