Granulomatosis with polyangiitis mimicking multisystem pyoderma gangrenosum: A case report.

Granulomatosis with polyangiitis, a type of small-medium vessel vasculitis, can pose diagnostic challenges due to its diverse clinical manifestations. We present a case that mimicked multisystem pyoderma gangrenosum with cutaneous ulceration, renal sparing, and antineutrophil cytoplasmic antibody negativity. Although antineutrophil cytoplasmic antibody is positive in approximately 90% of cases of granulomatosis with polyangiitis, its negativity should not exclude the diagnosis. Additionally, pyoderma gangrenosum-like cutaneous ulcers should prompt consideration of granulomatosis with polyangiitis, especially in the context of multisystem disease presentation. This case underscores the importance of maintaining a high suspicion for granulomatosis with polyangiitis in patients presenting with cutaneous ulceration and respiratory tract disease.