Severe Hypercalcemia and Acute Kidney Injury as Initial Manifestations of Multisystem Sarcoidosis in an Adolescent With Type 1 Diabetes: A Case Report.

Pediatric sarcoidosis is a rare noninfectious granulomatous disease that can affect any organ. Diagnosis is challenging due to a lack of specific tests and highly variable symptoms that can resemble infectious processes or malignancy. We report a 16-year-old Caucasian girl with well-controlled type 1 diabetes mellitus (T1DM) who presented with 10 days of nausea, vomiting, and generalized abdominal pain and was incidentally found to have severe hypercalcemia and acute kidney injury (AKI). Further testing revealed high 1,25-dihydroxyvitamin D (calcitriol) and angiotensin-converting enzyme (ACE) levels, with suppressed parathyroid hormone (PTH) and normal PTH-related peptide (PTHrP). An extensive infectious workup was negative. Imaging demonstrated generalized lymphadenopathy, raising concern for lymphoma or granulomatous disease. Lymph node biopsy showed non-caseating granulomas consistent with sarcoidosis. She received corticosteroids and steroid-sparing agents, resulting in normalization of calcium and symptom resolution. This case illustrates a rare, high-risk pediatric sarcoidosis with multiorgan involvement and severe hypercalcemia, emphasizing the need for biopsy confirmation and multidisciplinary evaluation in distinguishing it from infection or malignancy.