Yoichiro Chikamatsu, Izaya Nakaya, Mayumi Yahata, Hiroyo Sasaki, Kazuhiro Yoshikawa, Tsutomu Sakuma and Jun Soma
Background: Sarcoidosis is a multi-system disorder characterized by noncaseating epitheloid granuloma in multiple organs. However, granulomatous interstitial nephritis in the absence of extrarenal renal lesions is very rare.
Case presentation: A 64-year-old male presented with a weight loss of 10 kg and an increase in serum creatinine from 1.1 to 4.8 mg/dl over a 1-year period. At admission, no proteinuria or hematuria was found, although serum creatinine was 5.1 mg/dl and was associated with slight increases in serum angiotensin converting enzyme and calcium levels. Renal biopsy revealed granulomatous interstitial nephritis with noncaseating epitheloid cells. The patient was diagnosed with sarcoidosis, although no extrarenal sarcoid lesion was found. Oral prednisolone was effective, with normalization of serum creatinine levels 2 weeks later. A review of the literature showed that isolated granulomatous renal sarcoidsosis preferentially affected elderly males, and their serum angiotensin converting enzyme levels were normal or mildly increased in many cases.
Conclusions: This paper describes a rare case of isolated renal sarcoidosis with acute granulomatous interstitial nephritis. This case and a relevant review of the literature demonstrate that sarcoid granulomatous interstitial nephritis should be considered as one of differential diagnoses in elderly male patients with suspected tubulointerstitial nephritis irrespective of angiotensin converting enzyme levels.
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