Reversible Intrapulmonary Vascular Dilatation in a Patient Treated With Luspatercept for Myelodysplastic Syndrome.

A 70-year-old man with transfusion-dependent myelodysplastic syndrome was treated with luspatercept. Nine months into treatment and 2 months after dose increase, he developed new hypoxemia with a room air resting oxygen saturation of 88%. He was admitted, requiring up to 90% Fio2 by high-flow nasal cannula to maintain saturations ≥ 92%. CT scan demonstrated stable mild probable usual interstitial pneumonia, without ground-glass, pulmonary embolism, or arteriovenous malformation. Agitated saline contrast-enhanced echocardiogram was late positive, consistent with intrapulmonary shunt. Macroaggregated albumin (MAA) shunt scintigraphy demonstrated a shunt of 7.5%. Extensive investigations ruled out congenital portosystemic shunt and hepatopulmonary syndrome. We diagnosed hypoxemia from intrapulmonary vascular dilatation (IPVD), with luspatercept as a possible cause. Oxygen requirements improved, and supplemental oxygen was discontinued by 7 weeks after cessation. Repeat MAA 10 weeks after cessation confirmed shunt resolution (3.6% shunt). This case of reversible IPVD attributable to luspatercept highlights important monitoring implications in treated patients.