Canine cutaneous mast-cell tumors: Current concepts for patient management
Mast-cell tumors (MCT) often present a therapeutic challenge to practitioners due to their varied biologic behavior. Although many are cured with surgery, some MCTs require additional therapy for local and systemic disease control.
•The mast cell Mast cells originate in the bone marrow and migrate to peripheral tissues, where they are essential in allergic and inflammatory reactions. When mast cells are activated, they release preformed granules that contain histamine, heparin and proteases; this action is termed degranulation. Degranulation results in pruritus and swelling of the tumor or peritumoral tissue, excessive bleeding from the site of biopsy or fine-needle aspiration, delayed wound healing and gastrointestinal ulceration. The etiology of MCT is unknown. Although MCT are most commonly found in the skin and subcutaneous tissues, reports of primary MCT in visceral tissues and the nervous system exist.
•Initial therapeutic plan For most MCT, excisional biopsy after confirming the diagnosis via cytology is the initial treatment of choice. In dogs with large, infiltrative MCT that appear non-resectable or in patients with signs of mast-cell degranulation, such as peritumoral edema and bruising or gastrointestinal ulceration, additional staging is recommended prior to any attempt at surgical removal (Figures 2 and 3). For tumors not amenable to complete surgical resection or in patients with metastasis at diagnosis, chemotherapy and/or radiation therapy (RT) may be indicated prior to, following, or instead of surgery. In those cases, current therapeutic options should be reviewed, and consultation with an oncologist is indicated when available.