Carpal tunnel syndrome caused by synovial osteochondromatosis of the finger flexor tendon: A case report

RATIONALE: Carpal tunnel syndrome (CTS) is the most common peripheral nerve neuropathy resulting from compression of the median nerve as it traverses the carpal tunnel. The pathophysiology of this condition is multifactorial, and majority of cases of CTS are idiopathic. We report cases of CTS caused by synovial osteochondromatosis (SOC), which has rarely been reported. PATIENT CONCERNS: A 45-year-old female was admitted to the clinic due to right hand tingling sensation for 4 months. On physical examination, the patient's symptoms and signs corresponded to the median nerve entrapment at wrist. However, there is mild swelling and tenderness around the second metacarpal bone. Pain was aggravated during wrist and finger flexion. DIAGNOSES: An electrodiagnostic study revealed CTS. She was advised to begin splinting the hand using a wrist brace and to undergo physiotherapy. After 2 weeks, the tingling sensation decreased slightly. However mild swelling and tenderness around the second metacarpal bone did not improve. Ultrasonography showed multiple echogenic foci. Magnetic resonance imaging (MRI) revealed a nodule at the proximal metacarpal level with synovial thickening, enhancement, and a calcified shadow close to the flexor tendon. After confirming the presence of an osseous nodule with synovial thickening, the patient underwent surgery INTERVENTIONS: Carpal tunnel release and mass excision with synovectomy of the adjacent structures were performed. Histologically, the lesion was compatible with a diagnosis of SOC. OUTCOME: The symptoms have improved. LESSONS: CTS due to SOC on finger flexor tendon is rare but should be considered for possible etiology. Appropriate clinical examination, plain radiography, ultrasonography, and MRI will help physicians to diagnose this condition. In this paper, we report the successful diagnosis and treatment of CTS caused by SOC within the finger flexor tendon.