Lymphatic tumors are rare in pets. Lymphangiomas are benign and lymphangiosarcomas are malignant and have a moderate-to-high metastatic potential. Patients with lymphatic tumors typically have severe edema because of lymphatic obstruction. These types of tumors occur more frequently in young dogs and cats. Treatment usually involves surgical excision and chemotherapy may be used as a follow-up treatment in the case of lymphangiosarcomas.
Lymphocytes are specialized cells that function as part of the body's immune system, and are key cells in the body's ability to fight and prevent infection. Lymphocytes are found in the blood and tissues throughout the body, and are in particular concentration in lymph nodes and other 'lymphoid tissue'.
Lymphoma is a cancer of the lymphocytes. Lymphocytes are cells that are involved in the immune system. Lymphoma is connected with feline leukemia, a viral infection. Feline lymphoma most commonly affects the intestines. Therefore, clinical signs of lymphoma are often similar to other intestinal diseases. Diagnosing lymphoma requires finding cancerous cells on microscopic examination. Lymphoma cannot be prevented, but the likelihood of a cat developing lymphoma can be decreased by preventing feline leukemia virus infection.
The most common forms of cutaneous lymphoma are epitheliotropic lymphoma and dermal lymphoma. No specific risk factors or causes have been identified in the development of cutaneous lymphoma. Generally, cutaneous lymphoma can appear as various-sized irritated, ulcerated, or infected patches anywhere on the skin, including the gums, nose, or lip margins. These areas may become ulcerated and bleed, or become crusted. Secondary infections are possible. By far, the most common treatment for cutaneous lymphoma is chemotherapy. Unfortunately, the response to treatment, although initially encouraging, is typically short-lived, with gradual return of the tumors.
Mammary tumors in cats are not very common in North America due to routine spay procedures. Hormones play a role in tumor development in cats. Cats spayed prior to 6 months of age have a reduced risk of developing mammary tumors. Siamese Cats appear to be predisposed to developing mammary tumors. Mammary tumors are typically not painful and are usually discovered during a routine physical examination. Staging is recommended in all cases due to the tendency for these tumors to metastasize. Surgery is typically the treatment of choice and chemotherapy may be recommended after surgery.
A mast cell tumor (MCT) is a type of tumor consisting of mast cells. Mast cell tumors can form nodules or masses in the skin (and other organs), and cause enlargement of the spleen and intestine. Most mast cell tumors are seen as firm plaques or nodules in the skin. If your cat has the splenic form of the disease, the most commonly observed signs are weight loss, vomiting, and loss of appetite. The intestinal form, depending on how severe the disease is, may cause vomiting, diarrhea, fresh red blood in the stool, or black/tar-colored stool. This cancer is typically diagnosed via fine needle aspiration or biopsy. Surgical removal of the mass is the treatment of choice. Radiation therapy may also be suggested.
Melanocytes are cells that produce a pigment called melanin. A melanoma is an abnormal production of these cells in a dysregulated manner that forms a nodule, mass, or other form of lesion. Melanomas of the skin may develop anywhere on the body and are not typically bothersome. Toe melanomas, however, can be much more painful and concerning for your pet's health. Melanomas are often black in color but some do not produce pigment (amelanotic melanoma). Fine needle aspiration or biopsy may be used for diagnosis. Melanomas of the skin and toes are treated surgically and radiation therapy may be discussed.
The two most common nasal tumors are nasal adenocarcinoma and nasal lymphoma. Clinical signs range from mild to severe, and may include respiratory distress, hemorrhage, and neurological problems. Staging is always recommended before primary therapy is pursued. Radiation therapy is usually pursued for localized disease. Chemotherapy is usually pursued for systemic disease.
Neuroendocrine tumors are a group of tumors that develop from the cells of the neuroendocrine system, and include insulinomas, gastrinomas, glucagonomas, carcinoids, medullary thyroid carcinomas, small-cell lung carcinomas, pheochromocytomas, chemodectomas, and Merkel cell carcinomas. Some of these tumors are functional, while others are non-functional. The signs of disease in dogs and cats depend on the type of growth, location of the tumor, its size, the degree of infiltration in the surrounding tissues, whether it has metastasized, and whether it is functional. A definitive diagnosis requires tissue biopsy and histopathology, often with histochemical staining and electron microscopy. Staging is highly recommended for these tumors. Treatment may involve surgery, chemotherapy, radiation therapy, and medical and dietary management.