Recognizing Granulomatosis with Polyangiitis in Bullous Purpura Presentations

Granulomatosis with polyangiitis has a variable presentation making diagnosis difficult as it can be mistaken for IgA vasculitis which presents similarly. We report a case of granulomatosis with polyangiitis presenting with a bullous rash. Our patient was admitted for bullous purpura to the extremities, and reported symptoms of sinus infection, productive cough, and bilateral hearing loss which was first treated with Amoxicillin. Initially, drug-related IgA vasculitis was the leading diagnosis, given recent Amoxicillin exposure and bullous purpura findings. However, given the history of nasal involvement, hearing loss, and anti-proteinase 3 positivity, granulomatosis with polyangiitis was diagnosed per American College of Rheumatology criteria despite atypical bullous purpura. We highlight that the presence of a bullous rash does not exclude granulomatosis with polyangiitis. Timely workup with biopsy and anti-neutrophil cytoplasmic antibody positivity screening is imperative as early diagnosis of granulomatosis with polyangiitis can prevent long-term complications.