AVP and inappropriate ADH syndrome: When SIADH occurs in the context of malignant hematologic diseases (e.g., lymphomas, leukemia, MM, Waldenström’s macroglobulinemia (WM)), it is mainly ascribed to ectopic ADH secretion or increased interleukin-6 (IL-6) production from malignant cells, as well as to CNS infiltration [43,44,45,46,47,48].