Canine histiocytoma is a non-cancerous (benign) skin growth that commonly occurs in young adult dogs. This tumor is a rounded eroded growth, but is not a skin cancer. It originates in the Langerhans cells, immune cells that function to provide protective immunity to the tissues that are in contact with the outer environment — the nose, stomach, intestines and lungs, but mainly the skin's surface. These cells are also referred to as dendritic cells, and histiocytes.
Although histiocytoma can affect dogs of all ages, the incidence of this skin tumor is more frequent in canines less than 4 years old. Histiocytoma is common in certain breeds that include Boxers, Dachshunds,Flat-coated retrievers, Great Danes, Cocker Spaniels, Shetland Sheepdogs and Labradors. Even bulldogs face a greater risk of getting this benign tumor.
As the skin tumor is non-malignant, it does not cause any harm and there is no need to worry about it. This raised, hairless lump often appears suddenly, without prior warning. The good news is that the skin growth goes away on its own, without causing any problem.
Common symptoms associated with histiocytoma are:
Small, firm, dome or button-shaped masses on the skin surface
Rare autoimmune blistering (dermoepithelial) masses, which may be ulcerated
Fast growing, nonpainful, usually solitary
Common sites are the head, ear edges, and limbs
Occasionally multiple skin nodules or plaques