Pathology of lipomatous lesions in Proteus syndrome

Proteus syndrome is an extremely rare, complex hamartomatous disorder with markedly variable clinical expression. We present a case of Proteus syndrome with multiple disfiguring soft tissue masses that were present since early childhood. The lesions involved predominantly the right side of the body and included scoliosis, macrodactyly, and limited hyperostosis in the right foot. There was no evidence of cranial or skin lesions. The patient underwent multiple resections of soft tissue masses, including an amputation of the right foot because of severe gait disturbance. All specimens exhibited lipomatous lesions that were probably hamartomatous rather than neoplastic. She carried a diagnosis of neurofibromatosis for more than a decade, but a re-evaluation of clinical features and pathological findings prompted the diagnosis of Proteus syndrome. We believe that a more informed evaluation of the pathology material may help to identify this rare entity.