Granulomatosis with polyangiitis presenting as a renal tumor

Inflammatory tumors of the kidney are uncommon and include primary inflammatory processes and systemic diseases such as sarcoidosis, IgG4 disease, and granulomatosis with polyangiitis (GPA). There are approximately 15 cases of the latter in the literature. Tumors in GPA are well described and have been reported in several organs including breast, orbit, mediastinum, central nervous system, and especially the lung. We report the case of a 48-year-old woman who presented with diffuse frontal headaches. Imaging showed both a cranial/sinus and renal mass. The pathology of the dura and nasal sinus biopsies were unrevealing. A nephrectomy was performed that demonstrated a discrete lesion with extensive necrosis, granulomatous inflammation, and crescentic pauci-immune glomerulonephritis, findings consistent with GPA.