Pathology of spontaneous tumour lesions in pullets and adult chickens in commercial farms - Short communication.

Twenty pullets and adult chickens, aged 100 to 403 days, from several commercial chicken farms were examined by gross and histopathology. Grossly, all chickens had white-greyish masses in the visceral organs with or without enlargement of the peripheral nerves. Histopathological examination revealed Marek’s disease (MD) lymphoma, lymphoid leukosis (LL) and myeloid leukosis (ML) in 14/20, 5/20 and 1/20 of the chickens, respectively. Lesions of the sciatic nerves in chickens diagnosed as having MD lymphoma were various. No neoplastic and/or inflammatory cells were noted in the peripheral nerves of chickens diagnosed as having LL and ML. These results indicated that MD lymphoma could also develop in older chickens; thus, microscopic examination is needed to identify MD in older chickens showing lymphocyte-derived tumours.