Polypoid sarcoma of the pulmonary trunk: analysis of the literature and report of a case with leptomeric organelles and ultrastructural features of rhabdomyosarcoma.

A case of polypoid sarcoma of the pulmonary trunk is described in an 80-year-old woman who had a 21-year history of episodic chest pain and hemoptysis. Ultrastructural examination revealed Z bands, characteristic of rhabdomyosarcoma, and leptomeric organelles. This is the 60th reported case of sarcoma of the pulmonary trunk. Symptoms in reported cases were variable, usually caused by tumor emboli to the lungs or by right ventricular outflow obstruction. Angiography was diagnostic. The tumor was characteristically polypoid, often multicentric, and by definition was fixed to the pulmonary trunk or valves. Non-differentiated sarcoma (often uniquely pleomorphic) was found in 37% of patients, leiomyosarcoma (once confirmed by electron microscopy) in 17%, myxosarcoma in 13%, elements of rhabdomyosarcoma in 8%, fibrosarcoma in 8%, elements of chondrosarcoma in 11%, and 5% were malignant mesenchymomas. The authors suggest that these tumors originate from the undifferentiated tissues of the bulbus cordis and propose the name myenchymoma for the tumor.