Renal and Paraspinal Mass in a Patient with Granulomatosis with Polyangiitis: Does Biopsy of one Mass Reflect Pathology in the other

Granulomatosis with Polyangiitis (GPA) is a necrotizing vacuities affecting medium and small sized blood vessels and produces necrotizing granulomas often involving the upper and lower respiratory tract . GPA can present as tumor like masses in the breast and kidney [1]. However, an association between GPA and renal cell cancer has also been reported [2]. We report a GPA patient who presented with abdominal pain and was found to have a renal and paraspinal mass which were biopsied revealing two distinct pathologic entities. A 74 year old Caucasian male was diagnosed with PR3 ANCA positive GPA in 2010 when he presented with acute kidney injury and had biopsy proven pauci-immune glomerulonephritis. He achieved disease remission with remission induction therapy with glucocorticoids and Cyclophosphamide. He experienced a renal relapse in 2013 and achieved disease remission with glucocorticoids and rituximab. He presented in March 2016 with abdominal pain and was found to have a right renal mass and a paraspinal mass. Ultrasound guided biopsy of the renal mass revealed clear cell renal cell carcinoma. Four days after the biopsy, he was admitted with fatigue, night sweats and arthralgias. Laboratory data were notable for a rise in serum creatinine, proteinuria and hematuria. His inflammatory markers were elevated and his PR3 ANCA titer had increased by two fold. His B cells showed reconstitution. He underwent biopsy of his paraspinal mass which revealed necrotizing granuloma with no evidence of infection or malignancy. He was treated with glucocorticoids and rituximab. His serum creatinine improved and his hematuria and proteinuria resolved. His inflammatory markers normalized and his PR3 ANCA titer became negative. His repeat CT scan revealed improvement in the size of the paraspinal mass (Figure 1 and 2). He subsequently underwent cryoablation of his right renal mass in October 2016