The bumpy lumpy kidney that dumped protein: granulomatous glomerular and tubulointerstitial nephritis

A 44-year-old African-American man with a past medical history of dermatomyositis and polymyositis presented with symptoms of weight loss, an erythematous rash, polyuria, polydipsia, and fatigue. Initial laboratory values revealed serum creatinine of 1.76?mg/dl from unknown baseline and positive serology for antinuclear antibody and anti-Jo-1. Follow-up laboratory values months later included worsening serum creatinine of 3.42?mg/dl, serum calcium of 12.1?mg/dl, and urine protein-creatinine ratio of 1070?mg/g. Diabetes, infectious diseases, malignancy, vasculitis, and other autoimmune diseases were excluded by serology and on ultrasound-guided renal core biopsy of the left native kidney.