Left-sided cardiac obstruction due to a left ventricular haemangiosarcoma in a dog

An adult male Hovawart-Airedale mix was presented for vaccination. During the general clinical investigation, systolic cardiac murmurs grade 4/6 were detected at the left basal cranial position. A cardiological investigation was offered, but only performed eight weeks later, after two episodes of exercise-induced syncope. During cardiac sonography, a solid chambered cystic mass was shown that partially obstructed the left-ventricular outflow tract (LVOT). In the continuous-wave (CW) Doppler from the left-apical 5-chamber-view, the V-max of the LVOT measured 5.1 m/sec. The dog suddenly died eight days later. The pathomorphological examination of the heart revealed the presence of a 4.0 x 3.5 x 3.0-cm large mass, located in the free myocardial wall at the level of the left atrioventricular (mitral) valve, protruding into the ventricular lumen. A malignant infiltrative neoplasm of fusiform to pleomorphic tumour cells, which had formed erythrocyte-containing cavities, was detected histopathologically. Based on the positive immunohistochemical reaction of the tumour cells for von Willebrand factor VIII-related antigen, CD31, and vimentin, the neoplasm was diagnosed as a cardial haemangiosarcoma. In cases of masses located within the ventricular myocardium, primary heart tumours, such as haemangiosarcomas, should be considered in the differential diagnosis even though this is an unusual site.