Histopathology and Immunohistochemistry of tumors in animals attending veterinary teaching hospital

Abstract

We aim in the current study to investigate the pathology and incidence of tumors that are excised surgically in Veterinary Teaching Hospital. This study collected the tissue samples from animals from 1 October 2020 until 1 April 2021. These samples were collected from animals that undergo surgical procedures to remove neoplastic growths in their body. After tissue grossing, samples were collected from tumor mass, then fixed in neutral buffered 10% formalin for 72 hours, then processed to embedded in paraffin wax. A routine Harris’s hematoxylin and eosin stain were also used, histochemical stains such as Masson’s trichrome and PAS techniques were used as needed. In exceptional cases, IHC protocol was used for diagnostic steps to some types of tumors included in the current study. The antibodies that were used are Vimentin for canine osteosarcoma, P53 for squamous cell carcinoma, Mdm2 for ovine pulmonary adenocarcinoma, and CD10 for neoplastic lymphocytes. The result of the current study showed that the prevalence of tumor recorded was Marek’s diseases 22.8%, squamous cell carcinoma 22.8%, ovine pulmonary adenocarcinoma 15.4%, third eyelid adenoma 15.4%, canine osteosarcomas 7.4%, venereal transmitting tumors 7.4%, and feline mammary gland tumor 7.4%. Histological examination of feline mammary gland tumor composed from server infiltration of neoplastic cells, these neoplastic cells identified as lymphocytes in a fibrous stroma. Third eyelid adenomas in cats and dogs were composed of well-demarcated nodules containing neoplastic sebaceous cells present in glandular form and combined by hyperplasia of epidermis extended inside the neoplastic mass. Venereal transmitting tumor in cat composed from cells with a round to oval shape and the cytoplasm is poorly defined by routine stain, with dense fibrous tissue. Osteosarcoma in a dog has a pleomorphic nature with an anaplastic form composed of islands of osteoid materials, and the tumor is composed of three types of osteoblast, chondroblast, and fibroblast. Pulmonary adenocarcinoma in sheep composed of a nodular formation containing dense collagen fiber deposition with transformation of cells lining alveoli into cuboidal or columnar cells can also be observed in other air passages. Squamous cell carcinomas are primarily found in skin lesions associated with the formation of pathognomic lesions known as keratin pearls. This lesion is composed of the acentric layer of keratin produced by neoplastic keratinocytes. Marek’s disease was observed in visceral organs such as liver, lung, kidney, intestines, and spleen composed from pleomorphic lymphocytes, diffusely proliferating small-to-medium-size lymphoblast. In conclusion, the incidence of tumor in animals that attending Veterinary Teaching Hospital belong to the College of Veterinary Medicine, the University of Mosul was in general high in comparison to other studies in Iraq and other countries, this high incidence should pay attention to the causes of these cancerous conditions and their relation to environmental etiology.