THE VET’S GUIDE TO ONCOLOGY VOLUME TWO www.sashvets.com VOLUME TWO | CONTENTS 1. Lymphoma 4 2. Mast Cell Tumour 10 3. Soft Tissue Sarcoma 15 4. Osteosarcoma 20 5. Haemangiosarcoma 25 6. Oral Tumours 30 7. Anal Sac Adenocarcinoma 36 8. Client Care 41 CHAPTER ONE LYMPHOMA 3 1. LYMPHOMA DISEASE OVERVIEW In cats lymphoma typically manifests as one of the following: Lymphoma is a cancer that arises from an uncontrolled proliferation of lymphoid cells. As it § Gastrointestinal lymphoma (Gl): this is the is a cancer of a type of white blood cell, lymphoma most common form of feline lymphoma can arise within the lymph nodes or it can arise § Multicentric lymphoma in any site throughout the body. It is the most § Mediastinal lymphoma common cancer in cats and it is observed with § Central nervous system lymphoma relative frequency in dogs. § Ocular lymphoma In some cases, lymphoma may remain localised § Renal lymphoma within the lymphatic system or within its organ of § Nasal lymphoma origin. In most cases, lymphoma is multicentric, resulting in more widespread disease. While location is commonly used to describe lymphoma, there are other classification schemes Usually, the inciting cause of lymphoma is that are also used for both descriptive and unknown. In cats there is a significant correlation prognostic purposes. These characteristics include between the development of lymphoma and tumour staging and tumour grading. infection with FeLV and FIV. Both feline leukaemia virus and feline immunodeficiency virus are Tumour Grade known to contribute to the development of feline lymphoma, although this effect is more pronounced Tumour grade is often used to describe the with feline leukaemia virus. Fortunately, increases expected biologic behaviour of a tumour. in feline vaccination have decreased the incidence of feline leukaemia-associated feline lymphoma In dogs the most common grade of lymphoma and the overall rate of lymphoma diagnosis in is high-grade lymphoma. High-grade lymphoma young cats. is expected to develop more quickly and behave more aggressively than indolent (low-grade) In dogs the most common locations for lymphoma. lymphoma include: In cats the term large cell lymphoma is used to § Multicentric lymphoma: this is the most refer to the equivalent high-grade lymphoma; common form of canine lymphoma, affecting these aggressive lymphoma cells are large and the peripheral lymph nodes and internal organs immature. The term small cell lymphoma is such as the liver, spleen, and bone marrow used to describe low-grade lymphoma, in which § Gastrointestinal (GI) lymphoma: affects the the cells appear indistinguishable from mature stomach and intestines lymphocytes. § Cutaneous lymphoma: affects the epithelial tissues of the oral cavity, skin, nose, and Tumour Staging § Central nervous system (CNS) lymphoma: affects the brain and/or spinal cord Tumour staging describes the extent of spread of a tumour. 4 Lymphoma is staged as follows: The most common location for feline lymphoma § Stage 1: involvement of a single lymph node or is the gastrointestinal tract; therefore, affected single anatomic site cats typically present with GI signs. The most common signs of feline GI lymphoma are anorexia § Stage 2: involvement of lymph nodes on a single and weight loss, although vomiting and diarrhea side of the diaphragm (dogs) or a resectable may also occur. On abdominal palpation, diffuse gastrointestinal tumour with only local lymph intestinal thickening or a palpable abdominal mass node involvement (cats) may be noted; these findings may occur with both § Stage 3: generalized lymph node involvement low-grade and high-grade lymphoma. on both sides of the diaphragm (dogs) or extensive, unresectable abdominal disease Cats with multicentric lymphoma may present (cats) for lethargy, weight loss, anorexia, and other § Stage 4: involvement of the liver and/or spleen nonspecific signs of illness. Mediastinal lymphoma § Stage 5: involvement of the CNS and/or bone may cause respiratory difficulties or shortness marrow or any other organ. of breath. Central nervous system lymphoma may cause neurologic abnormalities or spinal abnormalities, while ocular lymphoma may CLINICAL SIGNS present as visual deficits or blindness. The clinical signs of renal lymphoma are typically identical to The symptoms of lymphoma can vary significantly chronic kidney disease. Nasal lymphoma typically and are largely dependent on the area of the body causes sneezing, nasal discharge, and visible facial that is affected with lymphoid proliferation. swelling. In dogs the most common manifestation DIAGNOSIS of multicentric lymphoma is generalised lymphadenopathy. Owners may notice lumps or Blood Tests and Imaging swellings at the sites of their dog’s lymph nodes, or enlarged lymph nodes may be detected during The workup of a patient presenting to the a veterinary exam. Other non specific clinical veterinarian for nonspecific signs of illness, such signs of multicentric lymphoma include weight as those seen with lymphoma, typically begins loss, lethargy, pale mucous membranes, icterus, with blood tests, including a complete blood count shortness of breath or exercise intolerance, (CBC) and serum biochemistry and urine analysis. increased thirst and urination. In many cases, the CBC of patients with lymphoma Other canine lymphomas will present with is normal. In some patients, however, CBC different medical histories and clinical signs. abnormalities may be observed. Potential CBC Gastrointestinal lymphoma in dogs typically abnormalities in lymphoma patients include: presents as vomiting, diarrhoea, and weight loss. Canine cutaneous lymphoma typically presents § Anaemia, leukopenia, or thrombocytopenia: as a visible lesion on the mucous membrane, or on these abnormalities may be caused by bone the skin, which may be ulcerative or plaque-like in marrow disease or immune-mediated cell appearance. Central nervous system lymphoma destruction may lead to neurologic deficits or spinal pain. § Lymphocytosis: may represent Stage 5 disease or lymphoblastic leukaemia In cats lymphoma very rarely presents as generalised lymphadenopathy. A cat with multiple § Polycythaemia: rarely associated with enlarged lymph nodes may have a different disease renal lymphoma, which results in abnormal process as an underlying cause, such as infection, erythropoietin production or idiopathic lymphadenopathy. § Neutrophilia, eosinophilia, monocytosis: associated with generalised inflammation 5 Serum biochemistry abnormalities are also hyperplasia or inflammation. variable, reflecting the degree of organ involvement. If fine needle aspirate is not diagnostic, biopsy may be required. § Hypercalcaemia: may occur in dogs with T cell lymphoma, associated with paraneoplastic Additional Diagnostics syndrome § Hypoglycaemia: reported in both cats and dogs Additional diagnostics are often recommended to § Hyperglobulinemia: may be associated confirm the diagnosis, provide valuable prognostic with inflammation or monoclonal antibody information, and guide treatment decisions. These production diagnostics include: § Azotaemia: associated with renal lymphoma § Immunocytochemistry: special stains can be § Elevated liver values: associated with hepatic used to distinguish between T cell lymphoma involvement and B cell lymphoma in dogs- and this can be § Panhypoproteinemia: associated with GI done on cytologic samples by Vetnostics lymphoma § Flow cytometry: this test can be used to Imaging in cases of suspected lymphoma may assess for the presence of certain cell markers, include thoracic radiographs and abdominal which may provide information on diagnosis ultrasound to identify extent of disease if needed. and recommended treatment protocols and prognosis Fine Needle Aspirates § Polymerase Chain Reaction Assay for Antigen Receptor Rearrangement (PARR): can help Fine needle aspirates are often taken from distinguish whether an increased lymphoid suspected sites of lymphoma. In the case of canine population is clonal (neoplastic) or is indicative multicentric lymphoma, aspirates can be obtained of inflammation/hyperplasia from multiple lymph nodes to improve diagnostic yield. The mandibular lymph nodes should be TREATMENT avoided, if possible, because oral inflammation can interfere with the ability to obtain an accurate Lymphoma is treated with chemotherapy. Specific diagnosis. In feline gastrointestinal lymphoma, treatment protocols vary depending on tumour ultrasound guidance may permit the aspiration of location, grade, and stage. a thickened region of intestine or an enlarged local lymph node. Canine multicentric lymphoma treatment depends on the results of immunophenotyping. Canine “Under the Microscope” B-cell lymphoma is typically treated with the “CHOP” protocol, which includes a combination of In high-grade or large-cell lymphoma, cytological cyclophosphamide, vincristine, prednisolone and examination of a fine needle aspirate will typically doxorubicin. Canine T-cell lymphoma is typically reveal a population of immature, large lymphocytes treated with the “LOPP” protocol, which includes a with abundant cytoplasm that make up >70% of combination of lomustine, vincristine, procarbazine the cell population.. and prednisolone. In some cases, single agents or smaller combinations of drugs may be used, but In low-grade or small-cell lymphoma, cytology these approaches are typically associated with less typically reveals a uniform population of favourable outcomes. lymphocytes that is relatively normal in Canine