TNF and POEMS syndrome: Factors that combine to produce increased vascular resistance (vasoconstriction, vascular wall remodeling, and thrombosis in situ), associated with overproduction of cytokines (IL-1β, IL-6, tumor necrosis factor-α, and VEGF), have been implicated in the pathogenesis of pulmonary hypertension in POEMS syndrome, as suggested for primary pulmonary hypertension [27, 28].