Case presentation

A 23-year-old right-hand-dominant male presented with a four-month history of progressive pain and swelling over the dorsal-medial aspect of the distal forearm. The pain was insidious in onset, gradually progressive, and aggravated by wrist movements. There was no history of trauma, fever, weight loss, or systemic symptoms. A preoperative clinical photograph demonstrating the swelling is shown in Figure 1.

Figure 1: (A-B) Preoperative clinical photograph showing swelling over the distal ulna.

On physical examination, a firm swelling measuring approximately 4 × 3 cm was noted over the distal ulna. The swelling was tender and non-mobile, with normal overlying skin. Wrist movements were mildly restricted due to pain. Grip strength was slightly reduced compared to the contralateral side. Neurovascular examination was normal, with intact radial and ulnar pulses and preserved sensory and motor function of the median, ulnar, and radial nerves.

Plain radiographs of the forearm demonstrated an eccentric, expansile lytic lesion involving the epiphysis and metaphysis of the distal ulna, with cortical destruction and absence of periosteal reaction (Figure 2). The lesion had an ill-defined zone of transition and extended subarticularly. Based on the radiographic features, the tumor was classified as Campanacci Grade III [4].

Figure 2: (A-B) Preoperative radiograph demonstrating an eccentric expansile lytic lesion involving the distal ulna.

Magnetic resonance imaging (MRI) revealed a well-defined, eccentric, subarticular lytic lesion involving the distal ulna, with cortical breach and surrounding marrow edema. A small area of soft tissue extension was noted without significant joint involvement.

Considering the aggressive nature of the lesion (Campanacci Grade III) and cortical breach, surgical management with en bloc resection of the distal ulna was planned after obtaining informed consent from the patient [1].

Under regional anesthesia, a longitudinal incision was made along the subcutaneous border of the distal ulna. Careful soft tissue dissection was performed while preserving the surrounding neurovascular structures. The distal ulna was resected with adequate margins (Figure 3). During intraoperative inspection, a small erosive area was noted on the adjacent ulnar surface of the distal radius (Figure 4). The lesion was excised with wide margins to achieve oncological clearance.

Figure 3: Intraoperative photograph showing en bloc resection of the distal ulna.

Figure 4: Intraoperative image showing a small lytic lesion on the ulnar aspect of the distal radius.

The extensor carpi ulnaris tendon was stabilized to maintain wrist stability. The wound was closed in layers, and a splint was applied.

Gross examination of the resected specimen revealed an expansile lytic lesion involving the distal ulna (Figure 5).

Figure 5: Specimen of the resected distal ulna along with excised lesion from distal radius.

Microscopic examination demonstrated numerous osteoclast-type multinucleated giant cells, evenly distributed among mononuclear stromal cells. The stromal cells showed oval- to spindle-shaped nuclei without significant atypia. No features of malignant transformation were noted (Figure 6).

Figure 6: Histopathological slide showing numerous osteoclast-like multinucleated giant cells among stromal cells consistent with giant cell tumor.

The lesion excised from the distal radius demonstrated identical histopathological features, suggesting contiguous tumor spread rather than a separate primary tumor. This finding is consistent with previously reported rare cases of adjacent bone involvement in GCT [2].

The postoperative course was uneventful. Wrist mobilization exercises were started after wound healing. A postoperative radiograph confirming adequate resection with maintained wrist alignment is shown in Figure 7.

Figure 7: (A-B) Postoperative radiograph showing distal ulna resection with maintained wrist alignment.

At the 12-month follow-up, the patient demonstrated full wrist range of motion, near-normal grip strength compared to the contralateral side, no evidence of local recurrence on radiographs, and no functional limitation in daily activities.