When "Pneumonia" Does Not Resolve: A Case of Pulmonary Embolism Leading to Cavitary Pulmonary Infarction.

Pulmonary infarction (PI) is a recognized but relatively uncommon complication of pulmonary embolism (PE). Because its clinical presentation and imaging findings often overlap with those of community-acquired pneumonia (CAP), PI is frequently misdiagnosed. Progression to cavitation is exceedingly rare and typically reflects extensive, irreversible parenchymal necrosis. We describe a 66-year-old woman with heart failure with reduced ejection fraction (HFrEF) and coronary artery disease (CAD) who initially presented with symptoms consistent with CAP. Although she initially improved, she re-presented ten days later with acute hypoxemic respiratory failure and a newly developed smooth-walled cavitary lung lesion. Chest computed tomography confirmed a submassive PE complicated by necrotizing PI and secondary abscess formation. Given the failure of conservative management and evidence of parenchymal gangrene with the need for source control, she underwent urgent right lateral thoracotomy with bilobectomy for source control. The post-operative course was complicated by refractory shock and pulseless electrical activity (PEA) arrest. Following goals-of-care discussions, the family elected to pursue comfort-focused care. This case shows the importance of systemic-to-pulmonary collateral circulation in preserving lung parenchymal viability. In patients with limited cardiovascular reserve, failure of bronchial arterial compensation can precipitate catastrophic necrotizing infarction. Clinicians should maintain a high index of suspicion for PI in cases of "nonresolving pneumonia," as early recognition may be critical in preventing progression to cavitary disease.