Vasculitic Mononeuritis Multiplex May Be Misdiagnosed as Carpal Tunnel Syndrome

'Carpal tunnel syndrome' and 'tennis elbow' as prodromes for granulomatosis with polyangiitis (formerly Wegener's granulomatosis)

A 62-year-old man presented with excruciating joint pains, back stiffness and numbness of his hands and feet. Over the past 18 months, he had experienced similar episodes for which the diagnoses of bilateral carpal tunnel syndrome and lateral epicondylitis had been made. Physical examination revealed polyarticular arthritis affecting the shoulders, wrists and right knee. Palpable purpura overlying the calves and ankles was present. Laboratory tests showed markedly elevated erythrocyte sedimentation rate and C-reactive protein in the setting of negative blood and urine cultures. Rheumatoid factor and antinuclear antibodies were negative. Chest CT demonstrated bilateral pulmonary infiltrates. A punch biopsy of the rash showed leukocytoclastic vasculitis. Anti-proteinase-3 titers returned strongly positive. A diagnosis of granulomatosis with polyangiitis was made. Treatment with high-dose steroids, followed by rituximab resulted in normalisation of inflammatory markers with subsequent resolution of joint pains, rash and pulmonary infiltrates and improvement of neuropathic symptoms.