Stones, Bones, and Groans with Cancerous Overtones - A Rare Case of Diffuse Large B Cell Lymphoma Presenting as Hypercalcemia

Abstract

Diffuse large B cell lymphoma (DLBCL) is a type of non-Hodgkin lymphoma that can present in a variety of ways including fever, weight loss, weakness, and drenching night sweats. Uncommonly, hypercalcemia of malignancy can be associated with DLBCL through multiple mechanisms that include synthesis of parathyroid hormone related peptide (PTHrP) or elevated calcitriol levels. It is estimated that hypercalcemia in the setting of DLBCL is present in 18% of newly diagnosed cases. This report details a case of an 80-year-old man with history of chronic anemia and CKD stage 3b that presented with weakness, decreased oral intake, and self-reported weight loss. Initial labs showed a corrected calcium of 14.1 mg/dL and normal phosphorous and alkaline phosphatase levels. PTH was decreased at 4 pg/mL. Serum protein electrophoresis and skeletal survey were unremarkable. A continued anemia of 8.1 g/dL in the setting of hypercalcemia prompted further investigation with endoscopy and colonoscopy which showed a large malignant-appearing mass in the mid gastric body. Pathology identified the mass as DLBCL germinal center type. Labs taken after endoscopy reported elevated 1,25-dihydroxyvitamin D levels, consistent with vitamin-D induced hypercalcemia seen in DLBCL. This case report highlights an uncommon yet important presentation of DLBCL. It is imperative that a differential diagnosis for undifferentiated hypercalcemia in an older patient should include malignancies such as DLBCL and workup should include extrarenal causes of hypercalcemia such as PTHrP production and calcitriol levels.