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,
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).
||The photo micrograph showing malignant melanoma with
sheets of large numbers of neoplastic cells (H and E x400)
||Mitotic figures, Hyperchromasia and Bizarre cells and
some neoplastic cells inside capillaries (arrows) indicating Metastasis
(H and E x1000)
RESULTS AND DISCUSSION
Regarding clinical, radiologic and histopathologic findings, lymphoma
was confirmed to be the problem. Just like most lymphomas, it was arisen
in the large and small intestine and mesenteric nodes.
Other affected organs, in approximate descending order of frequency,
include liver, kidneys, thymus, cervical lymph nodes, perirenal lymph
nodes, stomach, eye and inguinal lymph nodes. Most lymphomas are of B-cell
origin, although some are T-cell and most are composed of immature lymphoid
cells, with rare to frequent mitotic figures.
In one study leukemia, lymphoma and osteogenic and anaplastic sarcomas
develop in Syrian golden hamsters inoculated intravenously at 3 weeks
of age with simian virus 40, which is a papova virus (Diamandopoulos,
1972). In another study, DNA isolated from skin epitheliomas containing
papovavirus induced lymphomas within four to eight weeks in 40 to 50%
of newborn Syrian hamsters injected ( Graffi et al., 1969). Lymphoma
should be suspected when any abnormal abdominal mass was seen. Clinical
signs related to gastro intestinal system were seem to be related with
the pressure caused from huge abdominal mass.