Abstract Introduction Pulmonary veno-occlusive disease (PVOD) is a rare cause of pulmonary hypertension (PH) characterized by predominant postcapillary venular obstruction and impaired gas exchange. Carcinoid tumors can also cause severe hypoxemia through the release of vasoactive mediators that produce diffuse pulmonary vascular dilation, leading to diffusion limitation. The coexistence of these two pathologies is exceptionally uncommon. We report a patient with progressive, hypoxemia and PH found at autopsy to have concurrent PVOD and a metastatic carcinoid tumor with pulmonary vascular dilations. Case A 60-year-old man with hypertension, nonobstructive coronary artery disease, stroke, obesity, type 2 diabetes, chronic kidney disease, and remote colon cancer presented with hypoxemia of unknown etiology. His symptoms began after a viral illness in December 2023. Over the following six months, he was hospitalized multiple times for escalating hypoxemia, eventually requiring 6 L/min of oxygen at rest. Pulmonary function testing showed moderate restriction with a severely reduced DLCO (31% predicted), but CT chest revealed no evidence of interstitial lung disease. Rheumatologic, infectious, and sarcoidosis workups were negative. In June 2024, he was hospitalized for worsening hypoxemia. CT chest demonstrated minimal bibasilar dependent densities, peripheral pulmonary vascular dilations, and large mediastinal lymphadenopathy. VATS biopsy was attempted but aborted due to hypoxemia. Mediastinoscopy revealed benign lymphoid tissue. Right heart catheterization (RHC) demonstrated a pulmonary artery pressure (PAP) of 76/38 (mean 50) mmHg and a pulmonary capillary wedge pressure (PCWP) of 15 mmHg. He was diuresed and treated with steroids before transfer to our institution. V/Q scan showed no evidence of pulmonary embolism. Bubble study was inconclusive for shunt. A vasodilator challenge with IV epoprostenol reduced PAP but caused acute worsening of hypoxemia, suggestive of PVOD. Given his steroid dependence, obesity, and poor functional status, he was deemed unsuitable for transplant and elected to pursue comfort measures. Autopsy revealed thickened and hypertrophied vessels, intralobular septal thickening extending to the pleural surface, discrete foci of distended and proliferative capillaries, and well-differentiated neuroendocrine tumor deposits in the small bowel and liver. Discussion The patient’s course was notable for progressive hypoxemia, a severely reduced DLCO, and pulmonary hypertension with worsening hypoxemia following vasodilator therapy—findings consistent with PVOD. Autopsy confirmed PVOD and unexpectedly revealed metastatic intestinal neuroendocrine (carcinoid) tumor, whose hepatic metastases likely released vasoactive mediators causing diffuse pulmonary vascular dilation and intrapulmonary shunting, akin to hepatopulmonary physiology. This case highlights two distinct and extremely rare mechanisms of refractory hypoxemia occurring concurrently. This abstract is funded by: None
Shafique et al. (Fri,) studied this question.