Mastocytoma in dogs (Mast cell tumors)

About mast cell tumors:
 Mast cells are cells that "reside" in the body's connective tissues. They are most commonly seen on the skin, lungs, nose, and mouth of the dog. They will appear on the dog as a reaction from immune system reactions, allergic reactions, or inflammation; most commonly due to parasitic infestations, tissue repair, or angiogenesis. The mast cells are "derived" from the bone marrow. 

Mast cells are graded according the following: location in the skin, presence of inflammation, and on how they are "differentiated". The more differentiated a cell is, the more it is like a normal cell.

The grade scale is listed below:
Grade I: These cells are well differentiated with a low potential of metastasis
Grade II: These cells are intermediately differentiated or undifferentiated with a high potential of metastasis  
Grade III: These cells are poorly differentiated or undifferentiated with a high potential of metastasis

 The following dogs are more prone to Mastocytoma than other breeds: boxers, bulldogs, pugs, and Boston terriers. The average year for a dog to develop this type of cancer is 8 years old. 

Signs of Mastocytoma:
·        Tumor on the skin or under the skin (subcutaneous), may have been present for days to months

·      Tumor may appear to fluctuate in size

·      Recent rapid growth after months of inactive or subtle growth is common

·      Recent onset of redness and fluid build-up is most common with high-grade skin and subcutaneous tumors

·      Extremely variable; may mimic or resemble other types of skin or subcutaneous tumors (benign and cancer); may resemble an insect bite, wart, or allergic reaction

·      Primarily occurs as a single skin mass or subcutaneous mass, but may have multiple masses located throughout the body

·      Approximately 50 percent of all mast cell tumors are located on the trunk and perineum (the area between the anus and vulva in females, or the anus and scrotum in males); 40 percent are found on the extremities, such as the paw; and 10 percent are found on the head and neck region

·      Lymph nodes may be enlarged around the area of the tumor and may develop when a high-grade tumor spreads to the lymph nodes

·      Masses may be itchy or inflamed due to the higher level of histamines in the tumor

·      Enlarged liver and enlarged spleen are characteristic of wide-spread mast cell cancer

·      Vomiting, loss of appetite, and/or diarrhea may occur, depending on the stage of the disease

Symptoms are mostly related to the stage of the stage of Mastocytoma your dog is experiencing. Below is a list of the four stages:
Stage 1 is characterized by a single tumor without metastasis
Stage 2 is characterized by a single tumor with metastasis into the surrounding lymph nodes
Stage 3 is characterized by multiple skin tumors, or by a large tumor that has invaded subcutaneously
Stage 4 is characterized by the presence of a tumor, with metastasis to an organ or wide spread mast cell presence in the blood

 How is my dog diagnosed with Mastocytoma?
When taking your dog to the vet for a checkup, you should always be sure to tell the vet everything you know about your dog and what it's experiencing in order for a more accurate prognosis which can lead to a quicker diagnosis. In order for your dog to be diagnosed with Mastocytoma your vet will have to put your dog through several tests. The most important test is an examination of the cells taken from the tumor. The vet will examine the cells by using a fine needle to draw fluid/matter from the tumor. Your veterinarian may also examine a sample of your dogs lymph nodes, bone marrow, kidney, or spleen. To discover the grade of mastocytoma and the stage of cancer, a surgical tissue biopsy will be required. Also, to help discover the stage of cancer and the location of the tumor, your vet with take x-rays and/or ultrasound images of your dog’s chest/abdominal area. 

How is my dog treated for Mastocytoma?
Having surgery can cause histamines to be released into the blood stream from the tumor due to "manipulation". Large amounts of Histamines in the blood stream can cause negative effects to organs. Your veterinarian will prescribe antihistamines to help relieve the symptoms caused by this. The most sought after treatment is aggressive surgery to remove the mast cell tumor. A "microscopic evaluation" of the removed tissue will have to be done to determine whether or not the surgery was successful, and also to predict the "biological behavior" of the tumor. A more aggressive surgery may have to be performed if the affected cells move too close to the "surgical margins", if the lymph nodes become affected, or if the cancer spreads in general (however, this has minimal benefit for the dog). Chemotherapy is recommended after surgery to help reduce the chances of the cancer coming back (this is estimated to benefit the dog up to 2 months). Sometimes the cancerous tumor and/or the lymph nodes that are affected cannot be completely removed. In this case, the chemotherapy following the surgery will only have "short-term" benefit, while some effects of cancer will still be shown. Recovering period following surgery is between one to four months. In a case where aggressive surgery is not possible, radiation is the best treatment to pursue. Radiation may be done before surgery to reduce the tumor to a "microscopic volume" allowing for a better response to surgery. 

What do I have to look forward to?
Your vet will regularly "microscopically evaluate" your dog to check for new cancer, or growth of grade 2 or grade 3 tumors, If your dog is getting chemotherapy your vet will perform regular complete blood count tests. Your dogs immune system can be greatly affected from "cancer fighting drugs" so it is extremely important to keep your dog on a strict immune boosting diet.

The information in this post was found from a veterinarian approved site on pet health and nutritional information.

11/5/2015 14:20:03

These cells are poorly differentiated or undifferentiated with a high potential of metastasis


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