Fatal Acute Cor Pulmonale From Primary Peritoneal Tumor Microemboli

Abstract

INTRODUCTION: Microscopic pulmonary tumor embolism (MPTE) is a rare complication of cancer that is often overlooked and underdiagnosed. We present a patient with acute cor pulmonale and right ventricular infarction due to MPTE as the initial manifestation of an occult cancer. CASE PRESENTATION: A 45-year-old obese woman with no prior medical history was transferred to a tertiary medical center for subacute dyspnea progressive over the preceding week. Within an hour the patient developed a new rapidly progressing oxygen requirement. Urgent bedside ultrasonography showed a severely dilated right ventricle (RV) compressing the left ventricle. Despite aggressive resuscitative efforts the patient progressed to respiratory distress leading to shock and death in less than 12 hours. Autopsy revealed a severely dilated right ventricle without hypertrophy and acute right ventricular infarction. The lungs were grossly unremarkable with intact architecture and normal lobar configurations with no pulmonary artery thromboembolism identified. Microscopic histopathologic examination of the lung tissue demonstrated diffuse alveolar congestion with intact architecture. Most notably, malignant cells were found throughout the lymphovascular system (Figure 1) of both lungs, partially occluding much of the vasculature. The primary tumor was a previously undiagnosed peritoneal tumor with extensive microscopic tumor embolization resulting in acute cor pulmonale and right ventricular infarction. DISCUSSION: MPTE is a rare complication of cancer in which the neoplastic cells enter the systemic and pulmonary arterial systems and cause obstruction at the level of capillaries. While clinically uncommon, MPTE is not uncommon at autopsy, with rates ranging from 2.4% to 26%. Clinically, most patients with MPTE present as subacute cor pulmonale with delayed respiratory failure. However, definitive antemortem diagnosis is extremely difficult if not impossible unless there is high level of suspicion. In the present case, the acute clinical decompensation and lack of chronic inflammatory changes seen in the vessel walls indicate rapid MPTE deposition. CONCLUSIONS: This case highlights acute col pulmonale from tumor microembolism as the presenting feature of a fatal occult cancer in a young, healthy patient. MPTE should be considered in the differential diagnosis of unexplained subacute cor pulmonale even in the absence of a known underlying malignancy. Disclaimer: We were unable to reach the next of kin for permission.