Immune reconstitution inflammatory syndrome mimicking relapsing cryptococcal meningitis in a renal transplant recipient.

Immune reconstitution inflammatory syndrome (IRIS) is a rare entity that has been described recently in solid organ transplant (SOT) recipients. IRIS is characterized by an exuberant and dysregulated immune response following treatment of opportunistic infections. We describe here the case of a kidney transplant recipient who developed cryptococcal meningitis that was efficiently treated with antifungal therapy and decreased immunosuppression regimen. Eight months later, a paradoxical worsening of neurological symptoms and neuroradiological findings led to the diagnosis of IRIS. A short course of high-dose steroid therapy allowed complete resolution of neurological symptoms. This report highlights the challenge for physicians to distinguish IRIS from a relapsing cryptococcal infection. Clinical improvement of cryptococcosis-associated IRIS by anti-inflammatory drugs needs to be confirmed among SOT recipients.

Diagnostic performance of [(18)F]fluorodeoxyglucose positron emission tomography-computed tomography in cyst infection in patients with autosomal dominant polycystic kidney disease.

Cyst infection is a common complication of autosomal dominant polycystic kidney disease (ADPKD). Diagnosis is challenging with standard imaging techniques. We aimed to evaluate the diagnostic performance of [(18)F]fluorodeoxyglucose positron emission tomography-computed tomography (18-FDG PET-CT) for the diagnosis of cyst infections among ADPKD patients, in comparison with computed tomography (CT) and magnetic resonance imaging (MRI). All APKD patients who underwent 18-FDG PET-CT for suspected cyst infection between 2006 and 2013 in a French teaching hospital were included. Diagnosis of cyst infection was retained a posteriori on an index of clinical suspicion. 18-FDG PET-CT findings were was considered to be positive in cases of cyst wall hypermetabolism. CT or MRI findings were were considered to be positive in cases of cyst wall thickening (and enhancement if contrast medium was injected) and infiltration of the adjacent fat. A control group of ADPKD patients with 18-FDG PET-CT performed for other reasons was included. Thirty-two 18-FDG PET-CT scans were performed in 24 ADPKD patients with suspected cyst infection. A diagnosis of cyst infection was retained in 18 of 32 cases: 14 with positive 18-FDG PET-CT findings, and four false negatives. There were no false positives and no hypermetabolism of cyst walls in nine ADPKD control patients. 18-FDG PET-CT had a sensitivity of 77%, a specificity of 100%, and a negative predictive value of 77%. 18-FDG PET-CT allowed a differential diagnosis in three patients. In contrast, CT had a sensitivity of 7% and a negative predictive value of 35% (p <0.001 vs. 18-FDG PET-CT). Only eight MRI scans were performed. The diagnostic performance of 18-FDG PET-CT is superior to that of CT in cyst infections, for comparable radiation doses and with no injection of nephrotoxic contrast medium, in ADPKD patients.