Radiology Resident Case of the Week
Etiology/Pathophysiology
Pathology:
Sarcomas of the pulmonary arteries are extremely rare tumors, with approximately 110 reported cases; the majority of these are undifferentiated or intimal sarcomas, with only 5 reported true angiosarcomas.
Primary tumors of the heart and great vessels are not common, but the most common type is a sarcoma. The most common tumor of the heart and pericardium is a metastasis, although angiosarcomas, particularly of the right atrium may be seen
Most primary sarcomas of the elastic vessels (aorta and PA) are undifferentiated, aka intimal, sarcomas, while leiomyosarcomas predominate in the muscular arteries and great veins, e.g. IVC. The majority of aortic sarcomas involve the abdominal aorta, and the prognosis is poor; patients may present with symptoms related to tumor emboli or hypertension. Sarcomas of the IVC have the best prognosis, are more often seen in women, and may present with pain, Budd-Chiari syndrome, or IVC syndrome.
Miscellaneous
Angiosarcomas of the pulmonary arteries have an intermediate prognosis, and patients often present with recurrent pulmonary emboli. Indeed, pulmonary emboli in a patient with no risk factors should prompt consideration of a PA tumor. The masses are often large and mucoid, completely filling the vessel lumen.
Imaging
The PA chest film 
(Fig. 1) demonstrates a large left hilar mass, as well as some pleural-based opacities, and a questionable LUL nodule.
The V/Q scan 
(Fig. 2) demonstrates relatively normal ventilation of both lungs, with complete nonperfusion of the left lung. While a large embolus in the left main pulmonary artery could cause such a defect, it is unusual for a thrombus that extensive to completely spare the opposite lung; usually, additional perfusion defects would be seen. Consideration to an extrinsic mass/node causing compression of the PA, as well as of a primary PA tumor, should be given.
The chest CT 
(Fig. 3) demonstrates a soft tissue density mass completely occluding the PA and extending peripheral to the artery. Multiple pleural based opacities are also seen, consistent with infarcts. A nodule in the LUL representing metastatic tumor was also seen, not included on these slices.
An MR of the chest 
(Fig. 4) also demonstrates a left hilar mass with extension into the PA causing complete occlusion of the lumen.
Finally, an aortogram 
(Fig. 5) demonstrates complete lack of flow in the left main pulmonary artery.
DDX
It is often difficult to differentiate a primary pulmonary artery tumor from the more common extrinsic tumor with secondary invasion of the PA.
Key references
1. Raaf, H and Raaf, J. Sarcomas related to the heart and vasculature, Semin. in Surg. Oncol. 10:374-82, 1994.
2. Burke, A and Virmani, R. Sarcomas of the great vessels, Cancer 71:1761-73, 1993.
3. Goldblum, J and Rice, T. Epithelioid angiosarcoma of the pulmonary artery, Human Pathol 26:1275-77, 1995.
ACR Code
5.324
Keywords:
Angiosarcoma; Pulmonary Artery