Discussion

GCT is a benign but locally aggressive bone tumor that primarily affects young adults. The tumor most frequently involves the epiphyseal region of long bones and typically presents with pain, swelling, and limitation of joint movement [3,4].

While GCT most commonly affects the distal femur, proximal tibia, and distal radius, involvement of the distal ulna is uncommon [1,2]. Because of its uncommon location, the diagnosis may be delayed or confused with other lytic lesions, such as aneurysmal bone cyst, chondroblastoma, or giant cell reparative granuloma. Radiographically, GCT typically appears as an eccentric, expansile lytic lesion involving the epiphysis and extending toward the metaphysis, with cortical thinning and absence of periosteal reaction [4]. MRI helps delineate soft tissue extension and intra-articular involvement, guiding surgical planning.

Treatment options for distal ulna GCT include intralesional curettage with adjuvants or wide resection, depending on tumor grade and extent. In distal ulna lesions, en bloc resection is commonly preferred due to the expendable nature of the bone and the desire to minimize recurrence risk [1]. Following resection, the extensor carpi ulnaris tendon can be stabilized to maintain wrist function, as performed in our case.

Contiguous involvement of the distal radius in distal ulna GCT is extremely rare and has been reported in only isolated cases [2]. The present case highlights the importance of careful intraoperative evaluation of all adjacent bone surfaces to identify possible tumor extension and achieve complete oncological clearance.

Adequate surgical margins and long-term follow-up are essential, given the risk of local recurrence associated with GCTs [3].