Lymphoma in animals

Malignant lymphoma of the cat (syn. feline lymphosarcoma ) is a malignant ( malignant) tumor disease in cats ( Felidae ) in which mostly form solid tumors in the lymphatic organs ( lymphosarcoma ). It is the most common cancer in domestic cats, about a third of all neoplasias in these malignant lymphomas. Domestic cats are affected within the previously studied species most frequently of this particular tumor shape. The disease is comparable to the non -Hodgkin's lymphoma in humans. The clinical picture is highly variable and depends on the location and size of the tumor. The cure views with chemotherapy is not always satisfactory, in malignant lymphoma of the spinal canal it is bad.

• 5.1 Notes and references

Etiology

A possible cause of malignant lymphoma is the feline leukemia virus ( FeLV), a retrovirus. According to a Scottish study, only one-third of affected cats are in Europe but FeLV -positive, in fact North America is 70%. However, can also be in the majority of seronegative cats for FeLV antigen a typical, known FOCMA ( feline oncornavirus -associated cell membrane antigen), demonstrate. It is assumed that in the majority of cases was the organism is able to eliminate the virus, but only after the virus has led to a malignant transformation of lymphatic cells.

In response to the presence of FeLV antibody titer, a bimodal ( bimodal ) results Age frequency. While most diseases in FeLV - positive animals at the age of 3 years experience, the median age is FeLV -negative animals at 7 years. In principle, all breeds are susceptible. With the decline of FeLV vaccinations due to the occurrence of malignant lymphomas is not diminished. Especially in older animals only a few animals with malignant lymphoma are FeLV - positive according to recent studies. More recently, especially lymphomas occur in the intestine, correlations with inflammatory bowel disease and cat food and chronic inflammation will be discussed momentarily.

Another cat specific virus, feline immunodeficiency virus (FIV, feline immunodeficiency virus) is also brought to a much lesser extent with the development of malignant lymphomas in context. A combined effect of both viruses is discussed.

Classification

Several classification schemes are possible for malignant lymphoma, based on different criteria.

After the localization of the tumors is a modified WHO schema application. The frequency of the different forms varies regionally. The following list is sorted by the number of reported cases worldwide.

After the Rappaport classification, a distinction well or poorly differentiated, nodular ( nodular ) or diffuse large cell and small cell - lymphocytic and histiocytic malignant lymphoma.

After the dignity geringgradig ( about 10 %), moderate ( 35%) and highly malignant ( 55%) lymphomas can be distinguished.

After the output cells are T-cell tumors, which probably represent the main part, and distinguished B-cell tumors. The latter are mostly to be found in FIV -associated and gastrointestinal malignant lymphomas. A more accurate statement here can not yet be made because few studies used molecular markers for these lymphocyte subtypes.

Clinic

Clinical stages

On the extent of the disease and the location -dependent forecast is different 5 stages, wherein the stage I, the best, the stage V has the worst prognosis.

More lymph nodes of a region or a single tumor with regional lymph node involvement or an unresectable gastrointestinal tumor

Many lymph nodes affected or many tumors outside the lymph nodes or not rezezierbarer gastrointestinal tumor or the spinal canal outside the spinal cord ( paraspinal ) or epidural localized tumor

Mediastinal malignant lymphoma

A mediastinal malignant lymphoma is based on the lymphatic organs in the mediastinum. It is often the thymus, but also the mediastinal ( lymph mediastinal ) or sternum lymph nodes ( lymph sternales ) can be the starting point. This form occurs particularly among younger, FeLV - positive animals.

Clinically, these lymphomas express in general weakness and anorexia. Due to the narrowing of the lung and trachea in respiratory distress or increased respiratory rate. Due to the narrowing of the esophagus regurgitation or aversion to drinking may occur. The mucous membranes may be discolored bluish ( cyanotic ) or pale due to a lack of oxygen. In the percussion of the chest changes can occur.

An X-ray examination shows a shading in the precordial ( located in front of the heart) mediastinum. Differential diagnosis, fluid retention ( hydro, Pyo, chylothorax, feline infectious peritonitis) and diaphragmatic hernia should be excluded here. An ultrasonic examination can be useful to show the tumor, especially if it is combined with a liquid accumulation.

A diagnosis is possible through a biopsy of the tumor by fine needle aspiration and subsequent cytological examination.

Gastrointestinal malignant lymphoma

In this group lymphosarcoma of the gastro -intestinal tract or associated lymph nodes ( Lymphocentrum celiac, mesenteric cranial and caudal ) classified. Some authors also arrange lymphosarcoma of the liver in this group. You are in FeLV - positive animals rarely (10 % of cases), but frequent localization in older animals and predominantly B-cell tumors. These tumors can be as solitary nodules, but rarely also occur diffusely in the submucosa. Approximately 20% of cases affect the stomach, the rest of the intestine.

The clinical picture depends on the location. In addition to anorexia and emaciation may vomiting ( esp. in solid tumors ), diarrhea (diffuse ) and bleeding and anemia occur.

Larger solid tumors can be palpated through the abdominal wall under circumstances already. Further information can be a sonography, endoscopy or laparotomy. The diagnosis is made ​​by biopsy and cytology in turn.

Peripheral malignant lymphoma

When peripheral malignant lymphoma ( also multicentric leukemia ) the lymph nodes outside the body cavities are affected. This localization is in cats, unlike malignant lymphoma in dogs often. Clinically the disease manifests nonspecific, occur mostly on painless enlargement of the lymph nodes. Later metastases in the liver, spleen and bone marrow can occur.

The diagnosis is made by biopsy or removal of the entire lymph node and subsequent histological examination.

Leukemic leukosis

In the leukemic leukosis (or lymphoid leukemic form), the bone marrow is primarily affected and degenerated lymphocytes circulating in the blood ( leukemia). Fever, weakness, anorexia, jaundice, fever, anemia (anemia) and pale mucous membranes are common.

Other malignant lymphomas

Malignant lymphoma of the kidney account for approximately 15% of cases and occur mainly in older animals. The values ​​for blood urea and creatinine are elevated. In advanced cases, there is a renal failure.

Malignant lymphoma of the central nervous system usually come with FeLV -positive younger animals before or after chemotherapy of renal lymphosarcoma. The tumors occur primarily in the vertebral canal and the clinical picture depends greatly on the localization and the extent of spinal cord compression from. The neurological deficits ranging from paresis, ataxia, to hyperaesthesia. Radiographs can usually be no changes in the vertebral prove at best a myelography can bring evidence of a space-occupying process. Differentialdiagnositsch are a number of other central nervous system disorders exclude, where is best based on the VETAMIN D scheme.

Malignant lymphoma of the skin are rare and occur at most in very old cats ( > 11 years) on. In the epidermis so-called pseudo - abscesses may occur, or even deeper and more diffusely distributed collections of lymphocytes.

Other possible locations of malignant lymphomas are the nasal cavity, the conjunctiva and the eye.

Therapy

In FeLV - positive animals, a therapeutic trial is only useful if separate from other cat ownership is possible (single living indoor cat ), as these animals pose a risk for otherwise the cat population.

The agent of choice is chemotherapy has been established. In contrast to human medicine, this treatment shows only minor side effects and is well tolerated by cats. So far, several protocols have been proposed for chemotherapy, extensive clinical studies on comparability but are still pending. A common treatment regimen is the combination of vincristine, cyclophosphamide and prednisolone. With this so-called COP protocol remission rates of up to 80% could be achieved, it is particularly promising in mediastinal and peripheral lymphoid malignancies. After remission monthly treatment with doxorubicin or idarubicin is performed to prevent recurrence in most cases. The success of chemotherapy is not predictable and remission rates are lower than in dogs.

Local therapies ( surgical removal, radiation ) may be appropriate for individual tumors but also chemotherapy is then attached to relapse prevention.

The treatment of malignant lymphomas of the spinal canal is little success to date.