[Childhood-onset systemic polyarteritis nodosa and systemic lupus erythematosus: an overlap syndrome?]

We described herein a patient who presented an overlap syndrome of childhood-onset systemic polyarteritis nodosa and childhood-onset systemic lupus erythematosus. A 9-year-old girl presented tender subcutaneous nodules on feet, arterial hypertension, right hemiplegia and dysarthric speech. She was hospitalized due to stroke and left foot drop. Brain computer tomography showed ischemic stroke. Magnetic resonance angiography revealed stenosis in the middle cerebral and internal carotid arteries. Electroneuromyography identified a mononeuropathy of left posterior tibial nerve and she fulfilled the childhood-onset systemic polyarteritis nodosa validated criteria. She was treated with intravenous methylprednisolone pulse therapy followed by prednisone, that was progressively tapered, six months of intravenous cyclophosphamide and after that she received azathioprine for 19 months. At the age of 14 years and 9 months, she presented malar rash, photosensitivity, edema in lower limbs and arterial hypertension. The proteinuria was 1.7 g/day. Antinuclear antibodies (ANA) were 1/1280 (homogeneous nuclear pattern) and anti-dsDNA antibodies were positive. Renal biopsy showed focal proliferative and membranous glomerulonephritis. Therefore, she fulfilled the American College of Rheumatology classification criteria for systemic lupus erythematosus and she was treated with prednisone, hydroxychloroquine and mycophenolate mofetil. In conclusion, we described herein a possible overlap syndrome of two autoimmune diseases, where childhood-onset systemic polyarteritis nodosa occurred five years before the childhood-onset systemic lupus erythematosus diagnosis.