Granulomatosis with polyangiitis presenting as renal mass: a literature review of imaging findings

Background and Objective: To review the imaging findings from case reports existing in literature about granulomatosis with polyangiitis (GPA) presenting as renal mass. GPA, formerly called Wegener's Granulomatosis, is a chronic antineutrophil cytoplasm antibody (ANCA)-associated vasculitis having both granulomatosis and polyangiitis component. It causes vasculitis of small and medium sized vessels, mainly of upper and lower respiratory tract and kidneys. Most common renal manifestation is segmental glomerulonephritis with proteinuria. Extremely rare is GPA renal manifestation as a renal mass. Methods: Using PubMed Medline index and Google search, existing English language case reports were searched using key words and cross references. Key Content and Findings: A total of 27 reported cases on GPA manifesting as a renal mass were found in the literature, with the first case being described by Maguire et al. in 1978. Conclusions: Diagnosis of GPA presenting as a renal mass requires biopsy or nephrectomy. Imaging can hint towards a benign etiology and supplement biopsy results. In patients with renal masses and clinical suspicion of GPA, imaging (MR and PET) and biopsy should be utilized for diagnosis, so that these patients are subjected to less surgical morbidity. This review tries to compile all these cases, with emphasis on, and a table summarizing, those findings.