A case report of triquetral osteoid osteoma: from diagnostic challenge to complete recovery

BACKGROUND: Osteoid osteoma (OO) is a benign bone tumor that rarely affects the carpal bones, with triquetral involvement being exceptionally uncommon. When occurring in atypical locations, it often presents diagnostic challenges, leading to significant diagnostic delays and inappropriate treatment. This case highlights the importance of maintaining clinical suspicion for OO in young patients with chronic wrist pain, even when initial investigations suggest alternative diagnoses. CASE PRESENTATION: A 20-year-old male presented with a two-year history of progressive right wrist pain and swelling with marked nocturnal exacerbation. The patient had sustained wrist trauma four years prior, followed by a prolonged asymptomatic period before symptom onset. Physical examination revealed dorsolateral wrist swelling, focal tenderness over the triquetrum, thenar and hypothenar muscle wasting, and severely restricted range of motion. During the symptomatic period, the patient was evaluated by multiple specialists. Initial radiographs and CT scans were unremarkable. Subsequent contrast-enhanced MRIs demonstrated synovitis and diffuse bone marrow edema, prompting empirical treatment for inflammatory arthritis with methotrexate, prednisolone, and intra-articular corticosteroid injections, all without benefit. Serial re-review of the MRI identified a previously overlooked focal enhancing lesion. CT imaging was obtained, revealing a lucent nidus with a peripheral sclerotic rim and central calcification within the triquetrum, pathognomonic of OO. Given the lesion's proximity to the ulnar nerve and the patient's development of flank pain with proteinuria from prolonged NSAID use, open surgical excision was performed, and histopathological examination confirmed the diagnosis. The patient experienced immediate postoperative pain relief and progressive functional improvement, achieving flexion of 60 degrees with full extension at two months and complete pain-free recovery with full function at six months. CONCLUSIONS: This case underscores important lessons for clinicians: osteoid osteoma should be considered in the differential diagnosis of persistent wrist pain in young adults, even when the presentation suggests an inflammatory etiology; early CT imaging is essential when initial evaluation is inconclusive; bone marrow edema may obscure small lesions on MRI, requiring careful review; and surgical excision of the nidus achieves excellent outcomes when other interventions are less suitable.