Giant extra-articular synovial osteochondromatosis of the left proximal thigh: A case report.

Extra-articular synovial osteochondromatosis is a rare disease. The present study describes the case of a 46-year-old female who suffered from extra-articular synovial osteochondromatosis of the left proximal thigh with limited hip movement. The patient underwent a total tumor resection and recovered well. The tumor was 15×14×5 cm3 in size and located in the muscle gap. After a 3-month follow-up, the patient's left hip motion was improved and a computed tomography scan demonstrated no evidence of recurrence. However, the long-term efficacy of this procedure requires continuous observation of the patient. To the best of our knowledge, this is the first case of a giant extra-articular synovial osteochondromatosis of the proximal thigh muscle gap.