Unexpected Discovery of Renal Mass in a Patient with Granulomatosis with Polyangiitis: Accidental or Inevitable?

Granulomatosis with polyangiitis (GPA) is an uncommon disorder that mainly involves the upper and lower respiratory tract and kidney, presenting as sinusitis, saddle nose, otitis media, pulmonary nodule and cavity, rapidly progressive glomerulonephritis. It also affects skin, eye, heart, joint and nervous system. Renal involvement in GPA is commonly manifested as necrotising glomerulonephritis, while renal mass is very rare. We herein present two hospitalised cases with fever, pulmonary cavity and renal mass. Clinical course and examinations of the cases, from symptoms to diagnosis, will be discussed in detail, along with a relevant literature review of this unusual renal manifestation.