Mast cell tumor

Overview
A mast cell tumor is a type of tumor consisting of mast cells that is found in many species of animals. It is also known as a mastocytoma, which in human medicine can refer to an accumulation or nodule of mast cells that resembles a tumor.

A mast cell originates from the bone marrow and is normally found throughout the connective tissue of the body. It is a normal component of the immune system and as it releases histamine it is associated with allergic reactions. Mast cells also respond to tissue trauma. Mast cell granules contain histamine, heparin, platelet-activating factor, and other substances. Disseminated mastocytosis is rarely seen in young dogs and cats, while mast cell tumors are a common malignant tumor of the skin in older dogs and cats. Up to 20 to 25 percent of skin tumors in dogs are mast cell tumors, with a similar number in cats.