Acute Calcific Periarthritis of the 1st Metacarpophalangeal Joint: A Rare Diagnostic Challenge.

Introduction: Acute calcific periarthritis (ACP) is a self-limiting inflammatory condition most commonly involving the rotator cuff of the shoulder. Its presentation in the hand is rare and often mimics infectious processes, leading to potential misdiagnosis and inappropriate treatment. Prompt recognition through imaging is crucial for accurate diagnosis and management. Case Report: We present a case report of a 84-year-old woman who presented with acute pain, swelling, and erythema of the right thumb. Clinical examination suggested an infectious etiology; however, plain radiographs were obtained to further evaluate the condition. Results: Radiographic imaging revealed a well-defined, amorphous calcific deposit adjacent to the 1st metacarpophalangeal joint, consistent with ACP. No bony erosions or joint space narrowing was noted. Laboratory markers for infection were within normal limits. Under a digital nerve block, the patient underwent an ultrasound-guided barbotage procedure with needle aspiration and lavage, successfully removing most of the calcium deposits. A corticosteroid (triamcinolone) injection was then administered at the site. The patient experienced rapid symptom relief and full resolution within 2 weeks, without the need for antibiotics or surgical intervention. Discussion: ACP of the hand, although rare, should be considered in the differential diagnosis of acute monoarticular swelling, especially when infection is suspected but not supported by laboratory findings. Radiographic evaluation is pivotal for diagnosis and can prevent unnecessary interventions. This case highlights the importance of clinical-radiological correlation in recognizing atypical presentations of ACP and reinforces its self-limiting nature with conservative management.