Mononeuritis Multiplex as an Initial Presentation of Rheumatoid Arthritis: A Rare Case Report from Bangladesh.

Rheumatoid vasculitis (RV) is an uncommon extra-articular manifestation of Rheumatoid Arthritis (RA) that typically affects patients with a more aggressive form of the disease. The diagnosis of rheumatoid vasculitis is suggested based on clinical presentation, laboratory findings, and confirmed through biopsy. We describe the case of a 28-year-old man who initially presented with myalgia and weakness in all four limbs. Subsequently, he developed hypertension and testicular tenderness. Neurological examination revealed painful sensory-motor neuropathy involving the bilateral median and ulnar nerves, as well as the right tibial and left common peroneal nerves- findings consistent with mononeuritis multiplex. Laboratory investigations showed a high titer of rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) antibodies. He was treated with intravenous methylprednisolone (1 gm daily for 3 days), followed by oral prednisolone (1 mg/kg body weight) and six pulses of intravenous cyclophosphamide. This was later transitioned to maintenance therapy with azathioprine. The patient showed dramatic clinical improvement, and at one-and-a-half-year follow-up, he remained reasonably well. This case highlights that mononeuritis multiplex due to rheumatoid vasculitis can be the initial presentation of Rheumatoid Arthritis. Clinicians should consider this diagnosis in similar clinical scenarios, and prompt immunosuppressive treatment should be initiated to prevent further complications.