Renal confined sarcoidosis: Natural history and diagnostic challenge

Abstract

A 69 year old male referred to nephrology clinic for uncontrolled hypertension. During his follow up over two years, he developed renal disease and hypercalcemia. He was found to have monoclonal gammopathy (MGUS). Urinalysis was negative except for Monoclonal IgG on immunoelectrophoresis. Workup for malignancy was negative including chest X-ray and bone marrow biopsy. He progressed into renal failure and ended up on dialysis. Interestingly, the renal biopsy showed non-caseating granulomas, and the patient was diagnosed with renal confined sarcoidosis which is extremely rare. PPD was negative. He was treated with Prednisone 60 mg daily. Surprisingly, his kidney disease was not responsive to steroids. Despite improvement in his calcium with treatment, his kidney function did not improve and he remained on hemodialysis but needed to stay on small dose of Prednisone to keep his calcium under control. Our case is the first in the literature that demonstrates the natural history of renal-confined sarcoidosis. In addition, the presence of MGUS created a diagnostic challenge and delayed diagnosis of sarcoidosis. Although the renal biopsy did not show direct damage from MGUS, a potential relation between renal sarcoidosis and MGUS is worth studied.