Histiocytoma

What is it?

A cutaneous histiocytoma is a harmless tumor of Langerhans cells, a type of immune cell in the skin. It is common, especially in dogs under three years old, though it can occur at any age. Boxers, Great Danes, and dachshunds appear more susceptible. It is one of the few tumors the dog's own immune system can eliminate.

What signs should I watch for?

Look for a single raised, red, button-like bump, often hairless, that grows quickly over the first one to four weeks. It may ulcerate, itch, bleed, or become infected. Nearby lymph nodes occasionally swell, which your veterinarian should recheck. More than one tumor at a time is unusual and needs further investigation.

How is it diagnosed and treated?

Because other lumps can look similar, your veterinarian will usually take a needle sample or biopsy to confirm the diagnosis. Many histiocytomas are left to shrink on their own. If the bump ulcerates, bleeds, becomes infected, or does not shrink within one to two months, it can be removed surgically, which is usually a permanent cure. Antibiotics may be used for infection.

Can it be prevented, and what's the outlook?

• There is no known prevention.
• The outlook is excellent, as most regress over a few months.
• Keep your dog from licking, scratching, or biting the bump, and keep any ulcerated area clean.