Renal sarcoidosis: a rare case

Renal sarcoidosis

Sarcoidosis is a systemic inflammatory disease of unknown etiology. The pathogenesis rests on an aberrant T cell response to unidentified antigens in individuals predisposed by genetic and environmental factors. Increased expression of polarized macrophages and disequilibrium between effector and regulator T cells contribute to the formation of noncaseating granulomas, that are frequently found in affected organs. The main kidney abnormalities in sarcoidosis are granulomatous interstitial nephritis (GIN) and hypercalcemia-related disorders. The clinical diagnosis is difficult. The outcome is variable, ranging from spontaneous remission to end-stage kidney disease (ESKD). Early diagnosis and prompt treatment with corticosteroids can improve the prognosis. Hypercalcemia may be responsible for acute kidney injury (AKI) caused by vasoconstriction of afferent arterioles. Complications of persistent hypercalcemia include nephrocalcinosis and renal stones. In patients with ESKD, dialysis and transplantation can offer results comparable to those observed in patients with other causes of kidney failure. Based on a review of the literature, we present an overview of the etiopathogenesis, the renal manifestations of sarcoidosis and their complications, management and prognosis.

A Rare Case of Renal Sarcoidosis

Sarcoidosis is a multisystem granulomatous disorder characterized by non-caseating granulomas in multiple organs. It most commonly involves lungs and it is very rare to find isolated cases affecting other organ systems with no associated pulmonary findings. We hereby present a case of a young 30-year-old male who was referred to the hospital by his primary medical doctor due to right eye pain secondary to iritis and acute kidney injury (AKI). His initial laboratory studies revealed anemia, AKI, mild hypercalcemia, and the urinary analysis revealed proteinuria. Imaging studies were negative and a kidney biopsy was performed and showed results from the biopsy that revealed diffuse tubulointerstitial disease with early fibrosis, widespread moderate inflammation, multifocal tubulitis, and focal aggregate of epithelioid cells suggestive of granuloma consistent with sarcoidosis. The patient was treated with prednisone. Renal involvement of sarcoidosis is extremely rare (around 0.7%). It has a wide spectrum of presentation including abnormal calcium metabolism, nephrolithiasis, nephrocalcinosis, and acute tubulointerstitial nephritis with or without granulomas. This is a unique case as it shows renal sarcoidosis without coexisting pulmonary finding of hilar lymphadenopathy on chest X-ray. There are very few reported cases of renal sarcoidosis in the literature and this case can add to the pool of those cases. It also emphasizes the need for urgent renal biopsy in the settings of AKI associated with mild to moderate proteinuria. Lack of availability of comprehensive research on the disease may lead to misdiagnosis and delay in treatment.