Abstract
A 16-year-old previously well girl presented with bilateral painful lower leg swelling and non-pruritic blanching rash across her torso and upper and lower limbs. These symptoms started after commencing amoxicillin for presumed tonsillitis. She was diagnosed with serum sickness-like illness and started on non-steroidal agents. The rash and painful leg swelling improved over the next 48 hours. However, she subsequently developed fevers, cough and new-onset haemoptysis.She continued to deteriorate with increasing amounts of haemoptysis, work of breathing and escalating respiratory support requirements. Serial chest radiographs showed worsening lung consolidation and enlarging pleural effusion. A CT chest revealed extensive bilateral lung consolidation, most likely pulmonary haemorrhage. Subsequent investigations showed positive classic antineutrophil cytoplasmic antibody, confirming the diagnosis of granulomatosis with polyangiitis.