Vitamin D-mediated hypercalcemia in lymphoma: evidence for hormone production by tumor-adjacent macrophages.

摘要: Nearly one-half of all hypercalcemic patients with lymphoma present inappropriately elevated circulating concentrations the active vitamin D metabolite 1,25-dihydroxyvitamin (1,25(OH)2D3). However, cellular source hormone in lymphomas remains unclear. To address this, we report case a 75-year-old man hypercalcemia associated raised 1,25(OH)2D3 and suppressed parathyroid (PTH) levels. Positron emission tomographic (PET) computed (CT) imaging revealed presence large that was confined to spleen; subsequent pathological analysis showed this an intermediate grade B-cell lymphoma. After surgical removal spleen, serum calcium levels became normalized within 24 h. Immunolocalization D-activating enzyme 25-hydroxyvitamin D3-1α-hydroxylase (1α-hydroxylase) sections resected spleen staining negative cells but positive neighboring macrophages. This study indicates may be due, some instances, excessive extrarenal production 1,25(OH)2D3. Furthermore, by using immunohistochemistry assess distribution 1α-hydroxylase, have been able show for first time tissue macrophages, rather than actual tumor cells, are most likely ectopic enzyme. Based on study, propose abnormal synthesis is because paracrine regulation tumor-associated