Wegener's granulomatosis masquerading as a renal cancer: a case report and review of the literature.

A 32 year-old man presented with sinusitis, proteinuria, mononeuritis multiplex, very increased acute phase proteins. Anti-PR3 ANCA were detected and Wegener's granulomatosis (WG) was diagnosed. As abdominal tomodensitometry detected a tumoral process of the left kidney, a paraneoplastic vasculitis associated with a renal cancer was suspected. Biopsy of the mass showed fibrosis, inflammatory infiltrates and necrotizing granulomas. No malignant cells were detected. The outcome was favourable after administration of methylprednisolone and cyclophosphamide. Characteristics of the nine previously reported renal inflammatory pseudotumors associated with WG are discussed.