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Subject: Veterinary Pathology × Author: KANIMOZHI, G × End date: 2013 × Start date: 2012 × Type: Thesis ×
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    ThesisItemOpen Access
    PATHOMORPHOLOGICAL STUDIES ON LYMPHOSARCOMA IN PIGS
    (SRI VENKATESWARA VETERINARY UNIVERSITY , TIRUPATI – 517502. (A.P.) INDIA, 2013-12) KANIMOZHI, G; SAILAJA, N (Major); SUJATHA, K; ADILAXMAMMA, K
    ABSTRACT : Lymphosarcoma was found to be the most common neoplasm of the pig even more common than embryonal nephroma and it was frequently observed in less than 6 months of age. Porcine lymphosarcoma was assumed to be caused by a complex interaction of infectious, hereditary and environmental factors. As limited information is available regarding the lymphosarcoma cases, the present work was undertaken to study the pathomorphological changes in affected pigs. A total of 86 lymphosarcoma suspected cases of Large White Yorkshire pigs were examined. Among them, 30 pigs showed lymphosarcoma during 61-90 days of age which was the highest number, followed by 26 and 12 pigs between 31-60 and 91-120 days of age respectively. Both male and female appeared to be affected equally during 1-150 days of age. Externally, the affected pigs were highly emaciated with sunken eyes and pale conjunctival mucous membrane. The cyanotic discoloration on the ears, ventral abdomen and on the medial aspects of legs was noticed in few cases. Grossly, prominent changes were noticed in mesenteric lymph nodes and intestine and also in lungs, heart, liver, kidneys and spleen. The mesenteric lymph nodes were greatly enlarged, edematous, soft in consistency and often hemorrhagic. Five to six lymph nodes were coalesced together extended up to 10 cm in total length and showed mulberry fruit like appearance. The mesenteric lymph nodes showed grayish white colour with bulging on cut surface and indistinct corticomedullary junctions. The colon showed minute raised grayish white foci on serosa and flat circular white patches in the mucosa. In lungs small, firm, circumscribed grayish white nodule of 3 - 4 mm with grayish white cut surface was observed. The paleness of heart, mild to moderate enlargement of kidneys and splenomegaly, two to three times the normal size were noticed.Cytological studies revealed clusters of pleomorphic neoplastic lymphocytes with large round nucleus, 2-4 prominent nucleoli and basophilic cytoplasm in mesenteric lymph node, lungs and kidney and also in spleen, liver and heart. Admixed with neoplastic cells, a few plasmacytoid cells having eccentrically placed nuclei and basophilic cytoplasm were seen in mesenteric lymph node, lungs and spleen.Microscopic examination of the mesenteric lymph nodes revealed the replacement of normal architecture by sheets of immature lymphocytes having round nucleus, prominent nucleoli, basophilic cytoplasm and mitotic figures. Focal areas of karyorrhexis and pyknosis of nuclei in a few lymphocytes, binucleated lymphocytes and giant cells were also evident. In intestine, focal infiltration of neoplastic lymphocytes in mucosa, submucosa and muscularis was observed. In lungs perivascular, interalveolar and peribronchial aggregation of neoplastic lymphocytes and thrombus formation in blood vessels were observed. Mild infiltration of neoplastic lymphocytes was noticed in heart, liver, kidney and spleen. Immunohistochemically, mild expression of CD3 was observed in the cytoplasm of lymphocytes in the mesenteric lymph nodes and in the alveolar blood vessels of the lungs in randomly selected 10 samples. The electron microscopic studies of mesenteric lymph nodes revealed degenerative lymphocytes of different size and shape, vacuolated lymphocytes with eccentrically placed nucleus, irregular nuclei and nucleoli, margination of chromatin cytoplasmic and mitochondrial vacuolation and vesicular mitochondria. As more prominent lesions were observed in mesenteric lymph nodes and intestine, this may be considered as alimentary lymphosarcoma. The primary site of involvement would appear to be the mesenteric lymph nodes with metastases to the other organs is indicative of multicentric form of lymphosarcoma. It can be concluded that both alimentary and multicentric forms of lymphosarcoma were noticed. Slightly positive immunoreactivity to CD3 (T-cell marker) in mesenteric lymph nodes and lung indicates T-cell origin of lymphosarcoma.