Multiple peripheral nerve compressions related to malignantly transformed hereditary multiple exostoses

Autosomal dominantly transmitted hereditary multiple exostoses is an uncomm on disorder consisting of multiple projections of bone capped by cartilage, The lesions are most numerous in the metaphyses of long bones but may appe ar on flat bones. Sarcomatous transformation occurs in 1-25% of patients, W e report a 33-year-old man with sciatica, previously diagnosed as hereditar y multiple exostoses, presenting with multiple peripheral nerve compression s. Electrodiagnostic studies showed profound axon-loss multiple neuropathie s involving the sciatic, superior gluteal, and inferior gluteal nerves. Mag netic resonance imaging of the left pelvis showed a large mass in the sacra l area that was suggestive of a chondrosarcoma. An open intralesional excis ion biopsy confirmed chondrosarcoma transformed from chondromatosis. Excisi on of the lesion was effective in eliminating the impingement of nerves and retarding progressive osseous growth. We suggest that malignant transforma tion be suspected in cases with focal compression neuropathy of patients kn own to have multiple exostoses. Osteochondroma as a possible cause for comp ression neuropathy is discussed. (C) 2000 John Wiley & Sons, Inc.