Perlman syndrome is characterized principally by polyhydramnios, neonatal macrosomia, bilateral renal tumours (hamartomas with or without nephroblastomatosis), hypertrophy of the islets of Langerhans and facial dysmorphism.

A hemangioma is a benign tumor characterized by blood-filled spaces lined by benign endothelial cells. A hemangioma characterized by large endothelial spaces (caverns) is called a cavernous hemangioma (in contrast to a hemangioma with small endothelial spaces, which is called capillary hemangioma).