Pathological Study on the Prevalence and Morphopathological Patterns of Ovine Pulmonary Adenocarcinoma in Slaughtered Sheep in Semnan Province, Northeast Iran

Introduction: Ovine pulmonary adenocarcinoma is a spontaneous lung tumor caused by a retrovirus in sheep, sharing notable similarities with certain types of human adenocarcinoma.Materials & Methods: This study was carried out in Semnan Province, northeast Iran, for a period of six months from April to September ۲۰۱۶. A total number of ۴۰۷۹ local breed sheep, divided into three age groups as <۱, ۱–۲, and >۲ years old, were subjected to post-slaughter examination in the Semnan abattoir to detect any pathological lesions. Results: Macroscopic pneumonic lesions were found and detected in the lungs of ۲۵۹(۶.۳۵%) sheep. During the gross examination, ۱۸۹ lungs (۷۳%) were collected for more detailed histopathological analysis. These lungs were enlarged, did not collapse, and in some instances, contained a small amount of foamy fluid within the respiratory tract. Six (۳.۱۷%) of the ۱۸۹ suspected lung samples showed histopathological lesions indicating ovine pulmonary adeneomatosis (OPA). These six lungs macroscopically were so heavy and waterlogged. The damaged lung areas were solid and light grey, particularly in the ventral region or diaphragmatic lobes. All six affected lungs had consistent histopathological characteristics and displayed typical lesions associated with atypical OPA. These features included papillary projections within the bronchioles and alveoli, sparse connective tissue stroma, infiltration of mononuclear cells and connective tissue, as well as swollen, foamy macrophages in the alveoli and bronchioles near the neoplastic lesions. In one instance, in addition to these changes, a prominent feature of the classic OPA form was noted, characterized by the presence of fibrin casts and neutrophils in the bronchial and alveolar lumens. The affected regions were largely similar and aligned with findings reported in other studies. All six affected lungs were from sheep older than two years. Conclusion: There is often no clear distinction between atypical and classic OPA cases, and both forms can sometimes be found within the same lung.

کلیدواژه ها:

Histopathology ، Ovine pulmonary adenocarcinoma ، Slaughterhouse