Pulmonary artery myxoid liposarcoma mimicking chronic thromboembolic pulmonary hypertension: from diagnostic mimicry to refractory vasoplegia

Abstract

Introduction: Pulmonary artery sarcomas are rare malignant tumors that can closely mimic chronic thromboembolic pulmonary hypertension (CTEPH). Misdiagnosis not only delays oncologic management but may also result in an otherwise technically successful pulmonary endarterectomy being followed by an unpredictable systemic inflammatory response.
Case Presentation: We report a 40-year-old man with several years of progressive dyspnea and recurrent hemoptysis. Bimodal imaging with high-resolution CT (HRCT) and CT pulmonary angiography (CTPA) demonstrated a large central intraluminal mass in the pulmonary trunk, together with features of chronic thromboembolic disease. Preoperative hemodynamics showed severe precapillary pulmonary hypertension: pulmonary artery pressure 110/24 mmHg (mean, 63 mmHg), right atrial pressure 17 mmHg, and pulmonary vascular resistance 1100 dyn·s·cm⁻⁵ (13.75 Wood units). Bilateral pulmonary endarterectomy was performed under deep hypothermia and circulatory arrest. A pale-yellow, soft, coarsely granular tumor mass admixed with chronic organized thrombotic material was removed, with satisfactory clearance to segmental and subsegmental levels. Final histopathology identified myxoid liposarcoma. Because of severe reperfusion lung injury, central venoarterial extracorporeal membrane oxygenation (VA-ECMO) support was instituted; however, the patient developed refractory right ventricular dysfunction, profound catecholamine-resistant vasoplegia, and progressive multiorgan failure, with a fatal outcome during the second postoperative week.
Discussion: The terminal hemodynamic collapse probably reflected several superimposed mechanisms: prolonged cardiopulmonary bypass, hypothermia, and ischemia-reperfusion; extensive mechanical fragmentation of tumor tissue with release of damage-associated molecular patterns (DAMPs); and possible bypass-associated lipopolysaccharide endotoxemia. Convergence of these signals on Toll-like receptor/nuclear factor κB-dependent cytokine activation, inducible nitric oxide synthase expression, and excessive nitric oxide-mediated vasodilation provides a biologically plausible explanation for the refractory vasoplegia. Without serial measurements of endotoxin, DAMPs, and cytokines, this relationship remains a pathophysiological hypothesis rather than proven causation.
Conclusion: In the presence of a large, central, and mobile pulmonary artery mass, sarcoma should be actively considered in the differential diagnosis of CTEPH. Early suspicion alters not only the surgical and oncologic strategy but also perioperative inflammatory risk assessment and the content of informed consent.