Renal sarcoidosis: Local renal turgescence, hypermetabolic 18F-FDG lesions, and granulomatous interstitial nephritis.

Renal sarcoidosis is the most common cause of granulomatous interstitial nephritis (GIN) 1-2 and could present hypermetabolic lesions in 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) imaging of the active disease.3 A 29-year-old man with aggravation of renal dysfunction for one month underwent renal magnetic resonance imaging (MRI). His serum creatinine peaked at 5.11 mg/dl (452 μmol/L). The coronal (Fig. 1A) and axial T2-weighted MR images (Fig. 1B-C) revealed local renal turgescence (red arrows) mixed with atrophy (blue arrows) and multiple cysts (yellow arrowheads) in the medulla of bilateral kidneys.