CGR 9: OUT ON A LIMB: AN UNUSUAL CASE OF VASCULITIS

Abstract

A 23-year-old international student from Hong Kong, presented to hospital with a six week history of spontaneous left lower limb pain and swelling. Her mobility had gradually declined to the point that she was wheelchairdependent. The patient had a history of nephrotic syndrome in 2004, managed in Hong Kong. Initial renal biopsies were consistent with minimal change disease but follow-up biopsies in 2006 showed focal segmental glomerulosclerosis (FSGS). The renal disease was refractory to steroids, and she had received further treatment with cyclosporine, cyclophosphamide, rituximab and ongoing tacrolimus, mycophenolate mofetil and low dose prednisolone. The patient's leg swelling was not associated with systemic symptoms. Examination revealed non-pitting oedema, warmth and exquisite tenderness of the left calf. Pulses and capillary refill was normal. Inflammatory markers were elevated. Renal function and urinalysis was normal. A lower limb Doppler ultrasound was normal. MRI revealed diffuse muscle oedema suggestive of myositis. A muscle biopsy showed no evidence of significant muscle inflammation but necrotizing inflammation of medium blood vessels with fibrinoid necrosis. Autoimmune, myositis, vasculitic, infective and thrombotic screens were negative. A CT angiogram was reported as normal. The patient was commenced on pulse methylprednisolone and discharged on high dose prednisolone. She had a rapid symptomatic response, with resolution of muscle pain and ability to mobilise normally. Our impression was of probable polyarteritis nodosa (PAN), localised to the limb. We questioned whether her initial renal disease may also have been explained by PAN with secondary FSGS. Rituximab was recommended for ongoing disease control.