INTRODUCTION: Pulmonary tumor embolism is an uncommon cause of cor pulmonale. It can be difficult to differentiate clinically from acute pulmonary embolism or chronic thromboembolic pulmonary hypertension (CTEPH) and hence most often diagnosed postmortem. We report a case of transitional cell carcinoma tumor emboli diagnosed after a successful pulmonary thromboendarterectomy for CTEPH.
CASE PRESENTATION: A 55-year-old male with a history of bladder cancer diagnosed 5 years prior was referred to our clinic for evaluation of pulmonary hypertension. Two years previously he was found to have pulmonary emboli and recurrent bladder cancer extending to his right kidney. At the time an IVC filter was placed prior to nephrectomy. Since then he had been maintained on anticoagulation with no evidence of cancer recurrence. Due to progressive and severe dyspnea, an echocardiogram was performed revealing right ventricular dysfunction and severe pulmonary hypertension. He was started on sildenafil with no improvement. A ventilation perfusion scan showed multiple bilateral large unmatched perfusion defects. He underwent a right heart catheterization which revealed severe pulmonary hypertension, a pulmonary artery pressure of 87/37 (mean 57 mmHg) and a cardiac index of 1.39 L/min/m2. Pulmonary artery occlusion pressure was not obtained due to inability to advance the catheter beyond the main pulmonary artery. A CT angiogram of the chest confirmed extensive bilateral occlusive thrombi with complete occlusion of the right middle and lower lobar pulmonary arteries, the lingular and basal segmental branches of the left lower lobar artery and an incomplete occlusion of the right upper lobe artery. Urgent bilateral thromboendarterectomy was performed 5 days later for suspected CTEPH where chronic organized fibrotic thromboembolic material adhering to the vessel wall was removed. Post-operative hemodynamics were markedly improved, with mean pulmonary artery pressures less than 30 mmHg and a cardiac index greater than 2.5 L/min/m2. He had an uneventful recovery with marked improvement in exercise tolerance. Pathologic examination of the excised material from the pulmonary arteries unexpectedly revealed metastatic transitional cell carcinoma embedded in fibrin clot.
DISCUSSION: Pulmonary tumor embolism (PTUE) is clinically under-recognized, as 3-26% of patients with solid tumors have tumor cells in the pulmonary vasculature on autopsy(1). Microscopic and macroscopic emolization of tumor to the pulmonary vasculature is thought to lead to pulmonary endothelial injury and vascular remodeling further compounded by in situ thrombosis. Establishing the diagnosis of PTUE can be difficult. Imaging studies usually cannot differentiate between pulmonary embolus due to clot or tumor. Lung scintigraphy may show multiple subsegmental unmatched perfusion defects but is often normal. CT angiography may demonstrate filling defects in the main pulmonary artery and its branches. Echocardiography may also reveal elevated pulmonary artery pressures and right ventricular hypertrophy has been described at autopsy(2). Chemotherapy has been used to successfully treat PTUE due to chemosensitive tumors such as choriocarcinoma and cardiac lymphoma. Pulmonary artery embolectomy has also been reported to successfully treat pulmonary tumor embolism due to renal neoplasms extending from the IVC, but we are aware of only 3 other cases where thromboendarterectomy was performed for PTUE due to a non-vascular tumor(3). To our knowledge, this is the only case in the published literature that describes successful pulmonary thromboendarterectomy in a patient with PTUE due to transitional cell carcinoma. It was unclear in this case whether the tumor embolization preceded thrombus formation or vice versa. Although the patient had marked clinical and hemodynamic improvement, his long-term prognosis remains unclear.
CONCLUSIONS: Pulmonary tumor embolism causing pulmonary hypertension and cor pulmonale is rare but may be clinically and radiologically indistinguishable from chronic thromboembolic pulmonary hypertension. PTUE should be suspected in patients with CTEPH or pulmonary emboli who are not improving despite anticoagulation. Although its long-term prognosis remains unclear, PTUE may respond favorably to pulmonary thromboendarterectomy.
Reference #1 Roberts KE, Hamele-Bena D, Saqi A, Stein CA, Cole RP. Pulmonary tumor embolism: a review of the literature. The American journal of medicine 2003;115(3):228-232.
Reference #2 Shields DJ, Edwards WD. Pulmonary hypertension attributable to neoplastic emboli: an autopsy study of 20 cases and a review of literature. Cardiovascular Pathology 1992;1(4):279-287.
Reference #3 Paw P, Jamieson SW, others. Pulmonary thromboendarterectomy for the treatment of pulmonary embolism caused by renal cell carcinoma. The Journal of Thoracic and Cardiovascular Surgery 1997;114(2):295-297.
DISCLOSURE: The following authors have nothing to disclose: Maher Ghamloush, Kari Roberts, Cameron Wright, Gus Vlahakes, Nicholas Hill, Richard Channick
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