Mast cell tumor
| Mastocytoma | |
|---|---|
| Classification and external resources | |
| Specialty | oncology |
| ICD-10 | C96.2, D47.0 |
| ICD-9-CM | 238.5 |
| ICD-O | M9740/1 |
| DiseasesDB | 34450 |
| eMedicine | derm/258 |
| MeSH | D034801 |
A mastocytoma or mast cell tumor is a type of round-cell tumor consisting of mast cells. It is found in humans and many animal species; in human medicine it also can refer to an accumulation or nodule of mast cells that resembles a tumor.
Mast cells originate from the bone marrow and are normally found throughout the connective tissue of the body as normal components of the immune system. As they release histamine, they are associated with allergic reactions. Mast cells also respond to tissue trauma. Mast cell granules contain histamine, heparin, platelet-activating factor, and other substances. Disseminated is rarely seen in young dogs and cats, while mast cell tumors are usually skin tumors in older dogs and cats. Although not always malignant, they do have the potential to be. Up to 25 percent of skin tumors in dogs are mast cell tumors, with a similar number in cats.
Mast cell tumors are known among veterinary oncologists as 'the great pretenders' because their appearance can be varied, from a wart-like nodule to a soft subcutaneous lump (similar on palpation to a benign lipoma) to an ulcerated skin mass. Most mast cell tumors are small, raised lumps on the skin. They may be hairless, ulcerated, or itchy. They are usually solitary, but in about six percent of cases, there are multiple mast cell tumors (especially in Boxers and Pugs).
Manipulation of the tumor may result in redness and swelling from release of mast cell granules, also known as Darier's sign, and prolonged local hemorrhage. In rare cases, a highly malignant tumor is present, and signs may include loss of appetite, vomiting, diarrhea, and anemia. The presence of these signs usually indicates , which is the spread of mast cells throughout the body. Release of a large amount of histamine at one time can result in ulceration of the stomach and duodenum (present in up to 25 percent of cases) or disseminated intravascular coagulation. When metastasis does occur, it is usually to the liver, spleen, lymph nodes and bone marrow.
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