Feline Hemangiosarcoma Study Guide

Overview and Clinical Importance

Hemangiosarcoma (HSA) is a highly malignant neoplasm arising from vascular endothelial cells. While common in dogs, HSA is relatively rare in cats, occurring in approximately 0.5% of feline neoplasms. However, when it does occur, it carries significant clinical importance due to its aggressive behavior, high metastatic potential, and often poor prognosis. Understanding feline HSA is essential for the NAVLE as it represents a critical differential diagnosis for cats presenting with acute collapse, hemoabdomen, or cutaneous masses.

Unlike canine HSA where splenic involvement predominates, feline HSA shows a different distribution pattern with cutaneous and subcutaneous forms being more commonly diagnosed, likely due to their visible nature. Visceral forms in cats most frequently affect the liver, followed by the spleen, intestines, and abdominal lymph nodes. Recognition of species-specific differences is crucial for appropriate clinical management.

Etiology and Pathophysiology

Cell of Origin

Hemangiosarcoma originates from vascular endothelial cells or their precursors (hemangioblasts). These are the cells that line the interior surface of blood vessels throughout the body. Because blood vessels are present in virtually every tissue, HSA can theoretically arise at any anatomic location.