A case of vasculopathy of unknown etiology associated with fatal hydrops fetalis and review of the literature on intimomedial mucoid degeneration.

Non-immune hydrops fetalis (NIHF) has a high mortality rate [1]. Many etiologies of NIHF have been identified, including cardiovascular abnormalities, severe anemia, and genetic defects. In patients with cardiovascular etiology, structural malformations lead to fluid accumulation resulting in increased intravascular hydrostatic pressure. We report a fatal case of NIHF in a 31 week gestational age, Caucasian neonate with heart remodeling associated with a stenotic vasculopathy of the right pulmonary artery. The artery revealed partial occlusion with vascular wall abnormalities, including disarrayed smooth muscle fibers, hyperplasia within the tunica media, and myxoid change within the media and intima. Identical vasculopathy was also identified within a mesenteric artery, and this contributed to hemorrhage and early ischemic necrosis of the small intestine, discovered on postmortem examination.