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  • Author or Editor: Jun Sasaki x
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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.

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To demonstrate the relationship between tumour development and virus replication, eight specific-pathogen-free pullets of line P2 (Group P; 14 weeks old) and five adult chickens (Group A; 96 weeks old) were inoculated with virulent Marek’s disease virus (vMDV). Five chickens of Group P died or were euthanised due to moribund condition following the development of neoplastic lesions between days 53 and 91. On histopathological examination, these lesions were characterised by the proliferation of lymphoid cells of variable size. On analysis by polymerase chain reaction (PCR), the MDV meq gene was detected in Group P from day 21, and it was continuously identified in five chickens until they died or were euthanised. Abnormal signs and histopathological changes were not observed in chickens of Group A. The MDV meq gene was temporarily detected in some chickens of Group A, but it remained almost undetectable throughout the experimental period. In older chickens inoculated with vMDV, the onset of MD lymphoma development tended to be delayed as compared with the young chicks. The relationship between MD lymphoma development and virus replication in older chickens has been suggested. Our data might indicate the underlying existence of an age-related resistance to vMDV challenge.

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Authors: Jun Sasaki, Megumi Toyoshima, Yasuhiko Okamura and Masanobu Goryo

A 10-year-old castrated male Beagle dog was presented with a 2-month history of intermittent vomiting and abdominal pain. The dog was referred to the Veterinary Teaching Hospital at Iwate University for further evaluation, and a splenic tumour was suspected on the basis of ultrasonography and computed tomography. Surgery identified a large, solid, light-pink mass on the greater omentum with blood-coloured ascites in the abdominal cavity, and resection was performed. Microscopically, the mass comprised spindle-shaped tumour cells and scattered osteoclast-like giant cells. Most spindle-shaped cells were positive for vimentin, desmin, and smooth muscle actin (α-SMA), whereas osteoclast-like giant cells were positive only for vimentin. On the basis of histopathological and immunohistochemical findings, a diagnosis of leiomyosarcoma was made. To the best of our knowledge, this represents the first report of leiomyosarcoma associated with osteoclast-like giant cells developing from the greater omentum in a dog.

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Authors: Jun Sasaki, Yusuke Kuroda, Atsushi Ueki, Bhuminand Devkota and Norio Yamagishi

Abstract

A 1-day-old male calf presented with clinical signs of severe progressive abdominal distension. Abdominal radiographic and ultrasonic images revealed several loop-like structures in the small intestine, which were indicative of gas retention. Experimental laparotomy was performed. However, the calf died during surgery. At necropsy, a round, well-circumscribed mass (3 × 3 × 2.5 cm) was found in the jejunal wall, and the jejunal lumen was narrowed. The mass was firm and had white to grey appearance on the cut surface. Histologically, the submucosa and the muscle layer were diffusely thickened due to abundance of neural tissues comprising several fascicles of nerve fibres and large aggregates of ganglion cells. Some ganglion cells contained basophilic Nissl substances in their cytoplasm. Immunohistochemically, these cells were positive for S-100 and synaptophysin. Ultrastructural examination revealed that the neoplastic ganglion cells contained dense core vesicles in the cytoplasm. Based on these findings, the neoplastic lesion was diagnosed as ganglioneuroma in the jejunum.

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Authors: Jun Sasaki, Yusuke Kuroda, Atsushi Ueki, Bhuminand Devkota and Norio Yamagishi

Abstract

A 1-day-old male calf presented with clinical signs of severe progressive abdominal distension. Abdominal radiographic and ultrasonic images revealed several loop-like structures in the small intestine, which were indicative of gas retention. Experimental laparotomy was performed. However, the calf died during surgery. At necropsy, a round, well-circumscribed mass (3 × 3 × 2.5 cm) was found in the jejunal wall, and the jejunal lumen was narrowed. The mass was firm and had white to grey appearance on the cut surface. Histologically, the submucosa and the muscle layer were diffusely thickened due to abundance of neural tissues comprising several fascicles of nerve fibres and large aggregates of ganglion cells. Some ganglion cells contained basophilic Nissl substances in their cytoplasm. Immunohistochemically, these cells were positive for S-100 and synaptophysin. Ultrastructural examination revealed that the neoplastic ganglion cells contained dense core vesicles in the cytoplasm. Based on these findings, the neoplastic lesion was diagnosed as ganglioneuroma in the jejunum.

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