MON-342 Calcitriol-Mediated Hypercalcemia in Adrenal Diffuse Large B-Cell Lymphoma

Abstract

Background: Hypercalcemia of malignancy can present with a suppressed intact PTH level in response to various etiologies including elevated PTH-rP, increased calcitriol production via activation of the enzyme 1-alpha hydroxylase, or osteolytic bone lesions. PTH-independent hypercalcemia with elevated 1,25-dihydroxyvitamin D (calcitriol) levels should prompt evaluation for granulomatous disorders including sarcoidosis, tuberculosis, and lymphoma. Here we present a case of calcitriol-mediated hypercalcemia secondary to a rare, adrenal diffuse large B-cell lymphoma. Clinical Case: A 61-year-old female presented with fatigue, myalgias, and generalized weakness. On admission, calcium was 14.1 mg/dL (8.9-10.3), phosphorus 2.4 mg/dL (2.3-4) and iPTH was suppressed to 3.6 pg/mL (8.5-75). CT scan revealed a 30-35 Houndsfield unit, 14 x 9 x 13 cm left adrenal mass. Workup included PTH-rP 0.3 pmol/L (<2.0) and calcitriol 109 pg/mL (18-78). Serum and urine electrophoresis were negative for monoclonal protein spikes. Further hormonal evaluation revealed normal serum and urine metanephrines, 24-hour urine cortisol 64 mcg/24h (3.5-45), 8 AM cortisol 1.9 ug/dL following 1 mg dexamethasone suppression (<1.8), midnight salivary cortisol 87 ng/dL (<100), DHEA-S 16.2 mcg/dL (<15-157), and 11-deoxycortisol 24 ng/dL (10-79). Angiotensin-converting enzyme level was normal at 10 U/L (8-53). Her hypercalcemia improved with intravenous fluids and calcitonin. She was not a surgical candidate as PET/CT revealed multiple para-aortic and mesenteric hypermetabolic lymphadenopathy, left breast soft tissue density, and a lesion in the right posterior pelvis likely indicative of metastatic disease. Nuclear bone scan ruled out bone metastases. Para-aortic biopsy was considered technically difficult in this patient so she underwent CT-guided core needle biopsy of the adrenal mass which confirmed high-grade CD5-positive diffuse large B-cell lymphoma. Immunohistochemical staining was positive for CD20, BCL2, BCL6, MUM-1, and Ki-67 90%. She completed 6 cycles of chemotherapy with rituximab, cyclophosphamide, vincristine, doxorubicin, and prednisone (R-CHOP). Repeat PET/CT following completion of chemotherapy showed no residual disease however one month later, she presented with acute encephalopathy with MRI brain showing a large frontal lobe tumor concerning for relapse. She received 1 cycle of intrathecal methotrexate and cytarabine however these were discontinued due to severe deconditioning. She now remains on oral ibrutinib. Conclusions: Primary adrenal lymphomas are a rare cause of non-Hodgkin lymphomas with less than 150 cases noted in the literature. Lymphoma should be included in the differential of patients presenting with PTH-independent hypercalcemia given the aggressive nature of the disease and associated high mortality.