Histiocytoma

Also Known As: Button tumor

Transmission or Cause: A benign, usually self-limiting tumor of mononuclear white blood cells in the skin which are derived from epidermal Langerhans cells.

Affected Animals: Most common in younger (< 4yr) dogs.

Clinical signs: Usually a single, rapidly growing raised, round, hairless pink, red or ulcerated skin nodule. They occur most commonly on the head, ears and legs.

Diagnosis: Needle aspirate and/or biopsy of the nodule reveals round cells which are typical histiocytes +/- associated inflammatory cells.

Treatment: In most cases, these tumors will spontaneously regress within 2-3 months due to immune stimulation. Treatment with topical or systemic steroids is therefore unnecessary and may inhibit immune clearance of the tumors. Lesions which persist for longer than 2-3 months should be removed and biopsied, and excision is curative in these cases.

Prognosis: Good, as these tumors are benign.