Mast cell tumors arise most commonly in the skin. They develop from a normal component of body tissues called the mast cell that play a role in the process of tissue repair by releasing inflammatory mediators. Mast cell tumors in the skin of cats rarely spread to other organs (metastasize). If metastasis occurs, the intestines or spleen may be affected. The cause of mast cell tumors is unknown.

Among cats, the Siamese breed may be more commonly affected. Males and females are affected equally.

Most feline mast cell skin tumors can be managed by surgical removal. Some mast cell tumors in young Siamese cats may even spontaneously regress in time without any treatment.


Diagnosis and Treatment Notes:

  • Mast cell tumor is generally diagnosed by needle aspiration and microscopic examination of the cells. Biopsy of a mass is also diagnostic. Once diagnosed or suspected, cats with mast cell tumor should have chest and abdominal x-rays looking for spread of the tumor. Abdominal ultrasound may also be beneficial.
  • Treatment depends on the severity of the disease, your individual pet, and your veterinarian. Surgical removal of skin tumors is often curative but tumors can recur in other areas in about 30% of cats. There is limited information on the use of radiation and/or chemotherapy in treatment of systemic feline mast cell tumor. ¬†Discuss treatment details when your pet is diagnosed with this condition.


What to Watch for*:

  • Round, raised masses in the skin
  • Lack of appetite
  • Vomiting
  • Abdominal pain
  • Black tarry stools due to bleeding in the upper intestinal tract

*Please notify us if you notice any of the above signs or if you have any questions!