A histiocytoma is a common benign skin tumor of Langerhan's cell origin that usually goes away on its own in 2-3 months.

It is typically found in dogs less than 2 years of age but can be found in older dogs as well. Breeds prone to histiocytomas include Labrador Retrievers, Boxers, Staffordshire Terriers, English Bulldogs, Scottish Terriers, Greyhounds, Boston Terriers, Chinese Shar Peis, and Dachshunds.


  • Small, pink, firm, dome or button-shaped masses on the skin surface
  • Eroded (raw) surface Itchy, irritated
  • Fast growing in first 1-4 weeks, usually solitary
  • Common sites are the head, ear edges, and limbs

Because many other conditions can look the same, it is important to get the right diagnosis to confirm that it is a benign histiocytoma. Other possibilities include ringworm and various types of tumors such as mast cell tumors and melanomas.


Because some of the other possibilities can be more serious cancers, it is important to get an accurate diagnosis.

Options for diagnosis:

  • Fine needle aspirate - your veterinarian will use a needle to extract some cells and examine them with the microscope. This can give your veterinarian a good indication that a lump is a histiocytoma, but is not a definitive diagnosis.
  • Surgical biopsy and histopathology - removal of a small piece of the lump with sedation or anesthesia; should give a definitive diagnosis.
  • Lump removal and histopathology; should give a definitive diagnosis and potentially curative.


The quickest way to treat a histiocytoma is by removal, but many will regress in 3 months. A steroid cream can keep it from bothering the pet and may speed up resolution.

Reasons for surgical removal:

  • Ulceration, itching, secondary infection, and bleeding that can't be controlled
  • Rapid growth after one month
  • Change in size, shape or character

Home Care

Keep your dog from scratching, licking, or biting the lump. Any ulcerated area must be kept clean. After surgery, keep the incision site clean and dry and prevent your pet from rubbing, licking, biting or scratching.