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General Information

Histiocytomas are very common skin tumors in dogs but very rare in cats. These tumors are benign (non-cancerous) and usually affect younger pets. Boxers, Dachshunds, Cocker Spaniels, Great Danes and Shetland Sheepdogs are more susceptible to these growths than other breeds.

Histiocytomas usually occur singly on the head and face, ears and legs. Usually they are less than 1 inch in diameter, button- or dome-shaped, and ulcerated.

Important Points in Treatment

1. Surgical removal is almost always successful in eliminating histiocytomas. However, in most cases medical treatment and/or observation without surgery is be successful. In most cases we suggest watching these tumors for about 8 weeks before electing to remove them (if we have determined the likely diagnosis by cytology). It is important that the tumor be watched closely for abnormal behaviour. If it starts to grow rapidly, if it becomes infected or if it fails to regress within 3 months I will probably recommend that the tumor be removed and the tissue be submitted for pathological examination.

2. Sometimes injection of the tumor seems to increase the rate of regression of the tumors. It is still very important that the tumor regress (disappear) completely if this is done. Some other tumors that look very much like histiocytomas will decrease in size with the injections but will continue to grow later. It is very important that this type of tumor be removed and submitted for histopathology.

3. Surgical patients:

Check the incision at least once daily. Report any abnormalities to the doctor.

Restrict your pet's activity until the sutures are removed.

Your pet will be evaluated for suture removal in ____ days.

Notify the Doctor if Any of the Following Occur:

* Your pet develops more tumors.

* Your pet's tumor bleeds.

* Your pet's tumor appears red or swollen, or oozes fluid or pus.

* Your pet's general health changes.

Undestanding your pet's diagnosis

What is a histiocytoma?

Histiocytoma is a benign skin tumor. Histiocytomas develop from histiocytes. Histiocytes are scavenger cells of connective tissue. Histiocytes are found throughout the body, including the skin. Connective tissue is the supporting tissue of the body. Types of connective tissue include bone, cartilage, and ligaments. Benign tumors do not spread throughout the body. Benign tumors usually do not cause serious disease unless they grow in a vital organ.

What causes histiocytoma?

The cause is unknown.

What are the signs of histiocytoma?

The tumor is a small, firm, dome or button-shaped mass on the skin that may be ulcerated. It is usually a single mass that is fast growing (unlike most benign tumors that are slow growing) and nonpainful. Common sites to find histiocytomas are the head, ear lobe, and limbs. Some animals may have multiple masses.

How is histiocytoma diagnosed?

Histiocytoma is diagnosed by microscopic examination of a tissue sample of the tumor. It is important to distinguish histiocytoma from malignant skin tumors that can be life threatening.

How is histiocytoma treated?

Histiocytoma may shrink or resolve on its own without treatment within 3 months. If it does not resolve on its own, surgical removal or freezing usually cures the condition.

What is the prognosis (outcome) for pets with histiocytoma?

Prognosis for animals with histiocytoma is excellent. Some animals will not require treatment, as the histiocytoma will shrink on its own, while other animals will require surgical removal of the tumor.

The information on this page was obtained from the site www.vetmedcenter.com