Primary Pulmonary Artery Leiomyosarcoma Mimicking Pulmonary Embolism.

SESSION TYPE: Cancer Case Report Posters IPRESENTED ON: Tuesday, October 23, 2012 at 01:30 PM - 02:30 PMINTRODUCTION: Pulmonary embolism (PE) is the most common cause of filling defects of the pulmonary arteries as detected by CT angiography of the chest. We present here two cases of an unusual patho-etiology of pulmonary artery filling defects.CASE PRESENTATION: Case 1. A 63 year-old-male was evaluated for progressive dyspnea on exertion. He had a 20 pound weight loss. Auscultation was unremarkable. The initial chest X-ray showed an enlarged right hilum. The CT scan of the chest identified a large right hilar and mediastinal mass with invasion of pulmonary artery causing a filling defect (figure 1). The patient underwent bronchoscopy which was non-diagnostic. Mediastinoscopy was performed. Pathology revealed malignant epitheloid neoplasm with positive vimentin, desmin and muscle specific actin (MSA), consistent with a high-grade leiomyosarcoma (figure 2). The patient subsequently underwent uneventful right pneumonectomy. Case 2. A 51-year-old female with past history of right breast ductal carcinoma in situ was evaluated for progressive dyspnea. The CT angiography of the chest identified a PE completely obstructing the right pulmonary artery (figure 1). The patient underwent a PET scan which identified an enlarged right hilar adenopathy, with an SUV of 4.7. The patient subsequently underwent EBUS biopsies of the right lower paratracheal lymph node. Pathology showed spindled cells with moderate nuclear pleomorphism which were positive for MSA and calponin. The overall impression was compatible with a leiomyosarcoma. The patient opted for alternative medicine treatment.DISCUSSION: Leiomyosarcoma is the most common histologic subtype of pulmonary artery sarcoma (1). This tumor arises from mesenchymal cells of the intima, causing intraluminal vascular narrowing. The transmural spread of the tumor occurs in approximately 50% of cases (2). The most common presenting symptoms are dyspnea, cough, chest pain and hemoptysis (1). The CT angiography of the chest usually shows pulmonary artery filling defects and is often misdiagnosed as PE. Patients usually have no response to optimal anticoagulation (2). Diagnosis is commonly done by bronchoscopy, mediastinoscopy, surgical biopsy or autopsy. Our cases were diagnosed by mediastinoscopy and EBUS biopsy. Surgical resection is the main treatment modality. Leiomyosarcoma has a poor prognosis with a survival rate of only 6% at 5 years (2). Most patients die from right-sided heart failure secondary to outflow tract obstruction.CONCLUSIONS: We presented two cases of primary pulmonary artery leiomyosarcoma in an attempt to raise the awareness of this rare disease as a differential diagnosis of pulmonary artery filling defects.1) Ramp U, Gerharz CD, Iversen S. Sarcoma of the pulmonary artery: report of two cases and review of the literature. J cancer Res Clin Oncol 1992; 118:551-556.2) Kim JK, Gutierrez FR, Lee EY. Primary leiomyosarcoma of the pulmonary artery A diagnostic dilemma. J Clin Imaging 2003; 27:206-211.DISCLOSURE: The following authors have nothing to disclose: Thitiwat Sriprasart, Catalin Nicola, Eyad AlmasriNo Product/Research Disclosure InformationUCSF Fresno MEP, Fresno, CA.