Primary Hemangiosarcoma of the Falciform Fat in Seven Dogs (2007-2015).

Canine hemangiosarcoma (HSA), a malignant neoplasm of vascular endothelial or bone marrow progenitor cell origin, most often affects the spleen, heart, and liver and typically has an aggressive biologic behavior. Canine HSA arising from the falciform fat/ligament represents a rare anatomic variant, with only two reports in the veterinary literature. In this study, we describe the clinical presentation, treatment, and outcome of seven dogs with primary HSA of the falciform ligament. Histologic grade and mitotic score were not significantly associated with outcome. All dogs had the primary tumor surgically excised except for one diagnosed at necropsy. Median overall survival for all dogs diagnosed prior to necropsy was 339 days, and the 1 yr survival rate was 50%. Four dogs were treated with adjuvant chemotherapy and had a significantly longer median overall survival (394 versus 83 days) than those that did not (P = .018). Dogs with HSA of the falciform ligament may have improved 1 yr survival rates and longer median survival time compared with dogs with HSA in more common visceral locations.