An interesting case of fever, rash, and polyarthritis

Abstract

Introduction: Poncet's disease is a parainfective reactive arthritis seen with active tuberculosis (TB) where no mycobacteria can be demonstrated in the affected joints. This rare entity has been reported mainly with extrapulmonary TB, but very rarely associated with pulmonary TB and still remains a diagnosis of exclusion. Case Report: We report a case of a 15-year-old boy who presented to us on June 2018 with low grade fever, cough with mucoid expectoration, and bilateral symmetrical nonerosive polyarthritis along with palpable purpura of both lower limbs and buttocks. On extensive investigations, he was diagnosed with secondary pulmonary TB on the basis of sputum examination (cartridge-based nuclei acid amplification test, CBNAAT) and radiological findings. Ultrasonography of the affected joints showed synovial thickening with minimal effusion in right knee joint, whereas joint fluid CBNAAT was negative ruling out intraarticular TB. Investigations were extensively carried out to rule out other autoimmune/ infectious cause of the polyarthritis and rash, which was finally attributed to Poncet's disease.