PB0060 - A Pulmonary Embolism Not Responding To Anticoagulant Treatment? Case report of a Pulmonary Artery Sarcoma

Background: There are few case reports of patients with a pulmonary artery sarcoma (PAS) because it is an extremely rare disease. There is little evidence and we wanted to share our experience.

Aims: We report the case of a patient with the initial diagnosis of pulmonary embolism (PE). She presented a poor outcome despite anticoagulant treatment and was ultimately diagnosed with PAS.

Methods: A 46-year-old woman with no relevant medical history experiencing mild COVID-19 symptoms was admitted in a private clinic and diagnosed with PE in the main branches through a contrast-enhanced computed tomography (CT) of the pulmonary arteries.
Treatment was initiated with low molecular weight heparin (LMWH), switched afterwards to Apixaban. However, she presented a poor evolution over the following month, developing progressing dyspnea and chest pain. She underwent a follow-up CT that revealed predominantly right bilateral pleural effusion, and progression of the PE, so she was transferred to our center.
The effusion was a lymphocytic exudate with low ADA (adenosine deaminase) and the cell block resulted negative for malignant cells. The therapy was then switched to supratherapeutic doses of LMWH.
An echocardiogram showed newly onset severe pulmonary hypertension and persistence of the PE. A comprehensive thrombophilia study yielded negative results. The patient was referred to a specialized center for consideration of endarterectomy.
A follow-up CT, after thorough evaluation by expert radiologists, raised the differential diagnosis of PE vs. PAS. An endobronchial ultrasound-directed biopsy was positive for malignant cells, compatible with primary leiomyosarcoma of the bronchial artery.
The patient died before recieving oncologic evaluation and targeted treatment.

Results: Primary PAS has a dismal prognosis despite treatment. The diagnosis can be challenging due to non-specific symptoms and radiographic findings, and can lead to misdiagnosis.

Conclusion(s): When faced with a PE with torpid evolution despite proper anticoagulant treatment, PAS should be considered in the differential diagnosis.