Answer: Granulomatous TIN

 

The classic finding for renal sarcoidosis is that of a non-necrotizing granulomatous tubulointerstitial nephritis (Granulomatous TIN). However, on biopsy this finding is non-specific and thus the differential diagnosis would also include drug/hypersensitivity reaction, infections (i.e. mycobacterial, fungal), and autoimmune disease. Sarcoidosis is considered a diagnosis of exclusion and thus clinical correlation is required.