Case of the Month: Fibrosarcoma

Gunner’s story*

As Gunner the Doberman approached his fifth birthday, his human dad started to notice some lumps on and under his skin.  There was a large, soft lump on the right side of his chest, a smaller lump on his left lower back, and another on his right hind leg.

Gunner’s vet performed some preliminary tests on the lumps, determining that the one on his chest was a benign lipoma (fatty mass).  The other two lumps, however, were suspicious for cancer, and so Gunner was referred to a veterinary oncologist for further investigation and a treatment plan.

At the oncologist, a CT scan was performed to look for evidence of additional growths or spread.  He also had biopsies of his lymph nodes, liver, and spleen: common places for cancer to arise or spread.  Finally, new biopsies of his three masses were taken to better understand the behaviour of the cancerous cells.

Fortunately, Gunner’s CT scan and biopsies of his internal organs and lymph nodes were clear.  However, the lumps on his back and hind leg were determined to be a fibrosarcoma and a mast cell tumor, respectively.

About the Condition: Fibrosarcoma and Mast Cell Tumor

Fibrosarcomas are malignant tumors that arise from the connective tissue.  They are often found on or under the skin in dogs.  They are known to be locally aggressive and invasive, often spreading microscopic tendrils of cancerous cells throughout the surrounding tissue. They don’t tend to spread to other locations, but they can cause significant problems in their original location if not treated promptly.  Because of their locally infiltrative nature, fibrosarcomas have a high risk of reoccurrence after surgical removal.

Mast Cell tumors are another common type of cancer in dogs. They arise from blood cells, but are best known as lumps affecting the skin, though they can appear in any organ or tissue.  Some breeds of dogs are more prone to developing mast cell tumors than others. This type of tumor is infamous for being unpredictable.  Some grow slowly and don’t spread, while others are very aggressive, and can spread to the lymph nodes, spleen, liver, or bone marrow.  Mast cells also contain histamine, a compound best known for triggering inflammation and allergic-type reactions.  Histamine release from mast cell tumors can cause negative effects even at locations of the body that are distant from the visible mass.

Treatment

Because both of these tumor types had a potential have a very negative impact on Gunner’s health and longevity, surgery was planned to remove both masses, leaving generous margins around each lump in an attempt to get all microscopic traces of the cancer.

When the ability to remove all microscopic traces of a tumor are in doubt, many dogs will also receive chemotherapy, radiation, or immunotherapy to treat their cancer.

Claim Outcome

Over the course of a year, Gunner had many tumors evaluated and treated by both his regular veterinarian, and has cancer specialist. Costs for this care exceeded $12,700**. His Dad’s Pets Plus Us Accident and Illness Max plan reimbursed him more than $10,000 of those fees!  We know you’re in good hands, Gunner.