Sarcoidosis Presenting With Severe Hypercalcemia, Renal Dysfunction, and Bilateral Submandibular Swelling: A Case Report

Sarcoidosis is a multisystem granulomatous disease that can be complicated by severe hypercalcemia and renal dysfunction. We report the case of a 51-year-old man admitted with severe hypercalcemia, acute kidney injury, weight loss, and bilateral submandibular gland enlargement. The diagnostic workup revealed suppressed parathyroid hormone (PTH), elevated 1,25-dihydroxyvitamin D, hypercalciuria, mediastinal and hilar lymphadenopathy, and pulmonary ground-glass opacities. 18F-fluorodeoxyglucose PET/CT (18F-FDG PET/CT) showed increased uptake in the submandibular and parotid glands, suggesting inflammatory involvement; however, salivary gland sarcoidosis was not histologically confirmed. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) demonstrated non-necrotizing granulomas. Together with compatible thoracic imaging and a negative evaluation for alternative granulomatous disorders, this finding supported the diagnosis of pulmonary sarcoidosis. Renal biopsy showed chronic tubulointerstitial nephritis, and although this finding may be compatible with renal involvement in sarcoidosis, direct renal sarcoidosis was not histologically confirmed because of the absence of granulomas. IV fluids and pamidronate led to normalization of serum calcium levels before corticosteroid therapy. After the initiation of prednisolone, renal function and thoracic imaging findings improved, and proteinuria decreased. This case illustrates the importance of considering sarcoidosis in PTH-independent hypercalcemia, particularly when it is associated with renal dysfunction and systemic inflammatory findings, while distinguishing histologically supported disease from possible organ involvement.