Primary pulmonary artery leiomyosarcoma in an adult dog

A 7-year-old neutered female English Setter presented with syncope, anemia, and weight loss. Clinical examination revealed a systolic murmur and echoc ardiography demonstrated a mass on the pulmonic valve. Postmortem examinati on confirmed the presence of a pulmonic valve mass that extended along the pulmonary trunk and into the left pulmonary artery. Multiple pale nodules w ere observed in the right lung. Microscopic examinations of the pulmonary a rtery mass and the lung nodules revealed a pleomorphic population of spindl e cells often arranged in broad bands containing strap-like nuclei and eosi nophilic cytoplasm devoid of cross striations. The neoplastic cells express ed vimentin and alpha-smooth muscle actin but did not express desmin, CD31, factor VIII, or S100. The presentation, histological features, immunocytoc hemical profiles, and behavior of this tumor were indicative of a primary p ulmonary artery leiomyosarcoma with lung metastasis.