We describe a 21-year male with mood disorder on lithium therapy and psoriasis-like skin lesions presenting with rapidly progressive renal failure. The kidney biopsy showed acute tubulointerstitial nephritis with immunoglobulin G4-positive plasma cell infiltration. He was started on oral steroids with a provisional diagnosis of IgG4-related tubulointerstitial nephritis. All dermatological, psychiatric and renal manifestations dramatically improved, and he was taken off lithium. He had a relapse of his psychiatric symptoms on stopping steroids, and they again responded to steroids.