A case of acute kidney injury caused by granulomatous interstitial nephritis associated with sarcoidosis

Abstract

Sarcoidosis affects multiple organs including lung, heart and kidney. Sarcoidosis causes hypercalcemia, hypergammaglobulinemia, and rarely, granulomatous interstitial nephritis, resulting in renal stromal damage. Granulomatous interstitial nephritis is characterized as interstitial nephritis with noncaseating epithelioid granulomas. Diagnosing granulomatous interstitial nephritis before patient's death is challenging; hence, only few cases proven by renal biopsy have been reported till date. We present a case of acute kidney injury caused by granulomatous interstitial nephritis as a renal manifestation of sarcoidosis proven by renal biopsy, which can be confirmed by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography. Glucocorticoid therapy was helpful for improving and maintaining her renal function over a 6-year period.

Keywords: 18F-FDG-PET/CT; Acute kidney injury; Granulomatous interstitial nephritis; Sarcoidosis.

Fig. 1

Findings of abdominal echography and CT. Abdominal echography and CT on admission showing no remarkable findings in the bilateral kidneys. (a: abdominal echography, b: abdominal CT)

Fig. 2

¹⁸F-FDG PET/CT findings. a, c ¹⁸F-FDG PET/CT on admission showing ¹⁸F-FDG uptake within the multiple lymph nodes in the mediastinum (red arrows), the multiple nodular lesions in bilateral kidneys (yellow arrows), and spleen (green arrow). b, d Follow-up ¹⁸F-FDG PET/CT showing no remarkable ¹⁸F-FDG uptake

Fig. 3

Pathohistological findings of renal biopsy. Renal biopsy specimen showing interstitial nephritis with noncaseating epithelioid granuloma (arrowheads), consistent with granulomatous interstitial nephritis. (a periodic acid-Schiff, × 400, b periodic acid methenamine silver, × 400, c Masson trichrome, × 400). Immunofluorescence staining showing no remarkable findings (d IgM)

Fig. 4

Clinical course of the present case