Necrotizing Renal Vasculitis Associated with Sarcoidosis in a Patient with Esophageal Cancer: A Case Report.

Sarcoidosis is a multisystem disorder characterized by non-caseating granulomas, often involving the lungs and lymph nodes, but can affect nearly any organ. Renal involvement in sarcoidosis typically presents as hypercalcemia or interstitial granulomatous nephritis. Renal vasculitis, however, is an exceedingly rare manifestation. We present a case of a 74-year-old Japanese male who was diagnosed with esophageal cancer and underwent chemoradiotherapy. He presented with hypercalcemia and renal dysfunction, and laboratory tests revealed elevated serum creatinine and hypercalcemia. Fluorodeoxyglucose-positron emission tomography/computed tomography showed intense uptake in the gluteal and adductor muscles, with no recurrence of esophageal cancer. A muscle biopsy confirmed non-necrotizing granulomas. Despite correction of hypercalcemia, proteinuria and renal dysfunction persisted, prompting a renal biopsy. The biopsy revealed pauci-immune vasculitis, with fibrin deposition and destruction of the vascular elastic lamina, without granulomas. The patient was treated with corticosteroids, which led to significant improvement in renal function and proteinuria. This case highlights the rare coexistence of sarcoidosis and renal vasculitis. Thus, even in the presence of mild urinary abnormalities, renal biopsy should be considered in the diagnostic approach to sarcoidosis patients with renal dysfunction.