Spectrum of kidney disease in pediatric sarcoidosis

Kidney involvement in pediatric sarcoidosis is rare and often underrecognized, leading to diagnostic delays and treatment challenges. We report six patients with renal sarcoidosis to highlight their diverse presentations and outcomes and challenges in management.

Medical records of patients diagnosed with renal sarcoidosis during 2020-24 were reviewed. Sarcoidosis was diagnosed based on clinical and histological features and exclusion of alternative causes and managed according to unit protocols. Information on clinical features, laboratory and radiologic findings, histopathology, treatment, and follow-up were compiled.

We present six patients with sarcoidosis, presenting with kidney involvement at the age of 1.5-14 years, and followed up for 7-138 months. All patients had acute kidney injury (AKI) of whom two required hemodialysis. Proteinuria was present in all patients, while four patients had microscopic hematuria or leukocyturia. Hypercalcemia with hypercalciuria, distal renal tubular acidosis, and nephrocalcinosis were seen in five, two, and one case, respectively. Granulomatous interstitial nephritis was confirmed histologically in all cases. While initial therapy with corticosteroids led to clinical remission in all cases, five patients had nine relapses, necessitating second-line immunosuppression with mycophenolate mofetil, azathioprine, or methotrexate; one patient received antitumor necrosis factor therapy. Median eGFR at last follow up was 59.7 (range 12.7-132) ml/min/1.73 m²; three progressed to chronic kidney disease (CKD) stages G3-G5.

Kidney involvement in pediatric sarcoidosis manifests in diverse forms, ranging from isolated biochemical abnormalities to severe AKI. While prompt immunosuppression might preserve kidney function, patients require close monitoring for relapses, and progression to CKD.