What are lymphatic tumors?
Lymphatic tumors are abnormal growths that develop from the lymphatic vessels of the skin or subcutaneous tissue (tissues under the skin layer). Lymphatic vessels are a network of ducts and vessels that drain lymph (a fluid containing proteins and white blood cells) from body tissues and from lymph node to lymph node. The network of vessels pass through a series of filtering lymph nodes (glands) and eventually into the bloodstream.
What is a lymphangiosarcoma?
Some lymphatic tumors are benign (lymphangioma) and some are malignant (lymphangiosarcoma). Both types are soft, poorly defined masses that may cause fluid to leak out from lymphatic vessels. These tumors can occur on or in the body anywhere lymphatic vessels are located.
What causes these types of tumors?
The reason why a particular pet may develop this, or any tumor or cancer, is not straightforward. Very few tumors and cancers have a single known cause. Most seem to be caused by a complex mix of risk factors, some environmental and some genetic or hereditary.
Lymphangiosarcomas and lymphangiomasare quite rare and there does not appear to be a genetic or hereditary cause. These types of tumors are more commonly seen in younger dogs or cats. See the handout “What is Cancer” for more information.
What are the clinical signs of lymphatic tumors?
These tumors (both benign and malignant) cause fluid to leak from the lymphatic vessels, therefore, the most commonly seen sign is edema (swelling) in the area of the tumor. This may be particularly visible on pets with tumors affecting the limbs. Your pet’s skin or limbs may appear ‘puffy’. This can cause some discomfort due to the pressure caused by the edema around the limb. If the tumor is in the chest or abdomen, your pet may experience respiratory difficulty or abdominal distension. If the cancer has spread, your pet may lose weight, experience vomiting, or have diarrhea.
How is this cancer diagnosed?
Fine needle aspiration (FNA) may be performed. FNA involves taking a small needle with a syringe and suctioning a sample of cells directly from the tumor and placing them on a microscope slide. A veterinary pathologist then examines the slide under a microscope. These samples are not always valuable for diagnosis and instead a biopsy (surgical excision of a piece of the tumor) is required. Pieces of the tumor are then examined under the microscope. This is called histopathology.
If surgery is to be pursued, a CT Scan or MRI of the affected area may be required for surgical planning.
How does this cancer typically progress?
Lymphangiosarcomas have a moderate-to-high potential to spread elsewhere in the body. Therefore, routine staging (searching for potential spread to other locations in the body) is highly recommended. This may include bloodwork, urinalysis, X-rays of the lungs, and possibly an abdominal ultrasound.
What are the treatments for this type of tumor?
The most common treatment is surgery. Given how aggressive lymphangiosarcomas are, surgery is often followed by chemotherapy. In the case of benign lymphangioma, removal of the tumor and affected area often provides relief and no further treatment is necessary.