A histiocytoma is a type of benign tissue mass. While these tumours can develop in any dog, some breeds such as Labrador retrievers and boxers are more apt to develop histiocytomas, according to the Veterinary Partner. Dogs under two years of age can develop these masses on their ears and limbs, heads and necks. If skin mass don't resolve on their own, identification by your veterinarian is necessary to rule out possible malignant tumours.
Histiocytomas develop from Langerhans cells. Langerhans cells stem from a type of immune system cell known as histiocytes, according to Veterinary Cancer Care. Histiocytes try to fight foreign bodies in order to protect your dog's body from infections. When foreign substances contaminate Langerhans cells, the cells respond with the formation of histiocytomas. Infectious agents introduced through wounds or ticks can stimulate the growth of histiocytomas, according to Veterinary Cancer Care.
Histiocytomas manifest as small, red bumps on the surface of your dog's skin. These bumps are not painful and grow fast. Often, there is a lack of hair around the growth. Histiocytomas usually appear as a singular mass. In rare occurrences, dogs with immunocompromised systems and older dogs can develop multiple formations. Very rarely will histiocytomas develop into a malignancy.
Your veterinarian will either perform a biopsy or needle aspiration of a histiocytoma to help diagnose the mass. In instances of biopsy, sedation is performed to help remove an adequate sample. Full removal of a mass can also help determine if cancer is present. A needle aspiration can extract cells from the mass to analyse the cells on a slide. However, a needle aspiration can't examine the structure of the histiocytoma tissue, which means inaccurate results can occur.
Usually histiocytomas vanish within three months. Your veterinarian may opt to wait and see if the masses vanish on their own. If the masses don't recede, removal of the masses can help prevent ulceration and infections, which can occur with histiocytomas. Since bleeding at the site of histiocytomas can sometimes occur, removal is necessary to prevent infections.