Splenic sarcoidosis without focal nodularity: a case of 1,25-dihydroxyvitamin D-mediated hypercalcemia localized with FDG PET/CT.

Objective: To report an uncommon cause of 1,25-dihydroxyvitamin D (1,25[OH]2D)-mediated hypercalcemia associated with splenic sarcoidosis and illustrate the evaluation and potential role of fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in such patients.

Methods: We present detailed clinical features, laboratory results, imaging results, and pathology results for this rare entity, discuss evaluation and management options, and review previous literature.

Results: A 65-year-old male presented with symptomatic hypercalcemia, with a serum calcium level of 14.1 mg/dL 3 months after being initiated on ergocalciferol for vitamin D deficiency. He was found to have a suppressed parathyroid hormone level, normal 25-hydroxyvitamin D (25[OH]D) level, and elevated 1,25(OH)2D level. Extensive evaluation did not yield a definitive diagnosis. His calcium levels normalized and symptoms resolved on prednisone then recurred when prednisone was discontinued. FDG PET/CT showed intense uptake in the spleen. Splenectomy was performed, which resulted in resolution of hypercalcemia and yielded a diagnosis of splenic sarcoidosis.

Conclusion: Splenic sarcoidosis causing hypercalcemia has been rarely reported. Our case is unique in that the spleen lacked typical focal nodularity on cross-sectional CT imaging, which is expected in sarcoid involvement of the spleen. Our case adds to an emerging literature documenting the potential value of FDG PET/CT in localizing otherwise occult 1,25(OH)2D-mediated hypercalcemia.