Granulomatosis with Polyangiitis Presenting as a Renal Mass: A Scarce Case Report with a Review of the Literature

Abstract Wegener granulomatosis (WG) now known as granulomatosis with polyangiitis (GPA) is an uncommon autoimmune disorder of undivulged etiology affecting the respiratory tract including paranasal sinuses, nasal cavity, lungs, and kidneys predominantly. GPA presenting as a solitary renal mass is rarely seen. We present a case report of a 27-year-old female presenting with a right renal mass along with pain, low-grade fever, and arthralgia. Computed tomography scan of the abdomen revealed a hypodense low attenuated renal mass with indistinct margins. Ultrasound-guided biopsy revealed features typical of GPA. She was started on oral steroids (prednisolone 40 mg) and azathioprine. She developed pain, vomiting, and diarrhea after starting treatment with azathioprine. Azathioprine was stopped and rituximab 1 g weekly was started for 4 weeks followed by 500 mg 6 monthly injections. She got symptomatic relief at 4 weeks with a diminution of renal mass at 6 months follow-up. We report this rare entity of WG presenting as renal mass. Suspecting and diagnosing renal mass as a part of GPA prevented us from undertaking unnecessary surgical treatment in this patient. Medical treatment with steroids and rituximab is effective in inducing remission and maintenance.