Pathology of osseous and genitourinary lesions of Proteus syndrome

A male patient followed from the age of 3 to 25 years was eventually diagnosed as having Proteus syndrome. He was born with linear epidermal nevi of the neck and forearm and presented with macrodactyly of the right hand and progressive hemihypertrophy of the right lower limb recurring after multiple reduction operations. The bone ends showed disorderly overgrowth of hyaline and fibrocartilage mixed with collagen and bone, and early differential diagnoses included Ollier's disease. The child also had vertebral anomalies, scoliosis, a bony protrusion of the cranial vertex, and strabismus. In the second decade he developed gyriform swelling of the soles, retinopathy, bilateral papillary cysts of the epididymis, and a giant cyst of the left kidney with complex glandular foci. At 22 years a 3-cm meningioma containing adipose tissue was resected, and at 24 years a 3-cm cellular nodule of the rete testis with hyperchromatic foci, probably an adenoma, was removed. The features of Proteus syndrome were those of hyperplasia and neoplasia of mostly mesodermal tissues. Unlike other reported cases, overgrowth of a finger recurred at 25 years.