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

Abstract

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.

Keywords: extra-articular; left proximal thigh; pathology; surgery; synovial osteochondromatosis.

Figure 1.

Pre-operative imaging examination. (A) Plain radiographs demonstrating a huge, oval, calcified mass that contained multiple radiopaque bodies, located medial to the left proximal thigh (white arrow). (B) Computed tomography scan showing an irregular mixed density mass located in the gap between the anterior and posterior muscles of the left proximal inner thigh. Axial (C) T1-weighted images showing a homogeneous, low-signal intensity and (D) axial T2-weighted images showing a high-signal intensity containing certain areas of punctate low-signal intensity.

Figure 2.

Post-operative histological observations. (A) Gross appearance of the huge, smooth-surfaced, dark-brown membrane-like manifestations and several loose bodies after removal, ~15×14×5 cm³ in size. (B) Membrane-like manifestations demonstrating mature synovial tissue (HE staining; magnification, ×100). (C) Loose bodies showing mature cartilaginous tissue containing multiple chondrocytes (white arrow) and ribbon calcification (black arrow) (HE staining; magnification, ×100). HE, hematoxylin and eosin.