Granulomatosis with polyangiitis presenting as a renal mass successfully treated with rituximab

Granulomatosis with polyangiitis (GPA) is a granulomatous disorder usually associated with vasculitis involving the small and medium-sized blood vessels that affects the upper and lower respiratory tracts and the kidneys, but almost any organ can be targeted. The typical renal involvement of GPA consists of a segmental necrotising glomerulonephritis, but, very rarely, renal disease could appear as an isolated or bilateral renal mass, requiring a differential diagnosis from neoplasms or granulomatous infections. We describe a patient who, during tests for a kidney mass, was found to have pulmonary nodules suspected to be metastasis, successfully treated with rituximab.