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Tumors

  • 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.

  • There are several different types of malignant mammary tumors, with carcinomas being the most common. Carcinomas arise from epithelial (skin) cells, tubules of the mammary glands, or other cells found in the mammary chain. The size of the masses and their appearance may vary, but they are usually firm and nodular. Occasionally, the skin over the mass may ulcerate (open) and bleed, and the affected area may feel warm to the touch and become painful. Detecting and treating these tumors when they are small, and before spread has occurred, will provide your dog with the best chance for long-term control.

  • A mammary tumor develops because of abnormal replication of the cells that make up the breast tissue. In cats, most mammary tumors (80-96%) are malignant. Sexually intact cats have a seven-fold increased risk for mammary tumors compared to spayed cats. Detecting and treating these tumors when they are small, and prior to metastasis, provides your cat with the best chance of long-term control. Surgery is by far the best treatment and, given the high metastatic rate in these tumors, chemotherapy is typically pursued afterward.

  • Mast cells are a type of white blood cell that plays a large role in allergic response through degranulation. Mast cell tumors (MCT) can occur in the skin, spleen, or gastrointestinal tract of cats. Their cause is unknown; however, many affected cats show a genetic mutation in the KIT protein involved in replication and cell division. Cutaneous MCTs most often appear as hard pale/white plaques or nodules, often around the head and they may be itchy. Splenic MCTs cause decreased appetite, weight loss, and vomiting. Intestinal MCTs may cause GI upset and bloody stools, and a mass may be palpable. Diagnosis is typically achieved via fine needle aspirate although histopathology can be used. Treatment usually requires surgical removal of the masses or the spleen. Sometimes, chemotherapy or radiation is needed.

  • Mast cell tumors are most common in the skin of dogs and have a nodular, alopecic, sometimes inflamed appearance. These can be itchy and can fluctuate in size. They are generally easily diagnosed by fine needle aspirate but histopathology is needed to grade the tumor to determine the prognosis and best management. Tumors can range from lower-grade, with minimal metastasis and spread, to higher-grade, with a high risk of metastasis and local invasion. Treatment usually involves surgical removal with wide margins and, depending on complications, may require supportive treatment including chemotherapy, radiation therapy, and therapy to target the mutation that instigated the tumor.

  • 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.

  • Many herding breeds (most commonly Collies and Australian Shepherds) have a mutation at the MDR1 gene that makes them more sensitive to the negative effects of certain medications. These drugs include several antiparasitic agents (when given at high doses), the antidiarrheal agent loperamide (ImodiumĀ®), and several anticancer drugs. The effects of the mutation vary in severity, depending on whether the dog carries one or two copies of the mutation. There is a cheek swab or a commercially-available test that assesses blood samples for the presence of the MDR1 mutation.

  • 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.

  • Peripheral odontogenic fibroma (formerly known as fibromatous and ossifying epulis) is a benign, often slow-growing tumor that arises from periodontal structures. They can be further sub-classified as peripheral odontogenic fibromas and acanthomatus ameloblastomas. These tumors do not spread to other organs; however, extension to surrounding tissues is common. Treatment is dependent on size and location of the tumor. If surgery cannot be performed, radiation therapy is an excellent alternative for ameloblastomas given their high degree of response to radiation therapy.