Lymphoma in Syrian Hamster

INTRODUCTION

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Hamsters are increasingly being used as a popular pet animal in the world. Relatively high population of these animals in our country requires a good veterinary care of these animals.

Among hamsters diseases, lymphoma is the most common tumour. Hamster papilloma virus (HaPV) is seem to be the cause of this tumour. This virus belongs to the subgroup Papovaviridea and also causes keratinizing skin tumours of hair follicle origin. Lymphomas are usually arise in the mesentery, but can originate in the axillary and cervical lymph nodes. the tumours are frequently lymphoid but in older hamsters lymphomas are the most commonly observed neoplasms of haematopoietic system (Meredith, 2006).

CASE HISTORY

A 2.5 years old male Syrian hamster was referred to us with the history of history of emaciation, weakness, lethargy, diarrhea and some rectal bleeding. Palpation showed the presence of a great mass in the abdomen.

Radiography was performed and the mass was defined with a high density in abdominal cavity.

As the owner requested, the hamster was euthanized using Sodium Thiopental. in necropsy there was a huge mass filled approximately all of the abdomen. It seemed to be originated from mesentery. the mass involved the gastrointestinal wall and lymph nodes. Kidneys, liver, gonads and spleen were seemed normal. Dissected mass showed that the centre was necrotized and surrounded with a layer of approximately 2.5 cm tissue. Tissue samples were obtained from the mass and other organs and were fixed in 10% neutral buffered formalin, embedded in paraffin, sectioned and stained with hematoxylin and eosin.

In light microscope examination solid sheets of lymphoid cells were interspersed with variable numbers of other lymphoid types like immunoblast. They had a high mitotic index. reticular cells and macrophages scattered between lymphoid cells (Fig. 1, 2).

Fig. 1:	The photo micrograph showing malignant melanoma with sheets of large numbers of neoplastic cells (H and E x400)

Fig. 2:	Mitotic figures, Hyperchromasia and Bizarre cells and some neoplastic cells inside capillaries (arrows) indicating Metastasis (H and E x1000)