Histiocytoma is the term given to a type of benign growth of young dogs.
Histiocytomas are in a category of tumors called “round cell tumors.” Round cell tumors can range from benign to highly malignant and include mast cell tumors, plasmacytomas, transmissible venereal tumors and lymphoma.
One of the helpful features of round cell tumors is that they “exfoliate” well, meaning that it is reasonably easy to obtain cells for diagnosis using cytology or fine needle aspirate (FNA). Therefore, when we see a mass we can start with one of these less-invasive methods of obtaining a diagnosis and, if it is a round cell tumor, we have a good chance of obtaining a diagnosis without having to go further.
If one’s dog must have a tumor, histiocytoma is the one to have. Not only is it benign, it goes away on its own. They can be recognized by their dome shape and hairlessness, location on the body and youthfulness of the patient. Median age of appearance is three years.
A pet owner must be careful not to be tempted to make the diagnosis himself. If wrong, you might be waiting for a mass to go away that will meantime be metastasizing, spreading cancerous growths to all points in the body. Instead, have your veterinarian evaluate the growth and obtain laboratory specimens if he deems that necessary.
Typically a histiocytoma lesion will begin to fade approximately four weeks after it appears, and be gone by six
weeks. Researchers believe that it is an immune system attack which results in the destruction of the tumor. Indeed, lifetime immunity may be conferred, as dogs rarely suffer relapses of histiocytoma.
See you tomorrow, Dr. Randolph.
