Dysgerminoma in an Arabian filly.

The research reports on a rare case of an ovarian tumor, known as a dysgerminoma, found in a young Arabian horse. The horse displayed signs such as weight loss and severe anemia. The cause was traced to a large growth replacing the left ovary and smaller tumors in other parts of the digestive system.

Introduction

This article discusses a unique case of a yearling Arabian filly (a young, female horse) referred to the Veterinary Medical Teaching Hospital due to severe weight loss, profound anemia, and peritoneal effusion (an excess accumulation of fluid in the abdominal space). Post-mortem investigation led to the discovery of a large, soft, irregularly colored neoplastic mass located at the pelvic inlet which had replaced the left ovary. The filly also manifested smaller tumor nodules disseminated throughout various internal surfaces such as mesentery (fold of membrane), diaphragm, and serosal surfaces of the abdominal viscera (internal organs).

Examination and Findings

• In histological assessment, the tumor was found to comprise of large round to polygonal cells cluster with a segmenting effect caused by fibrous connective tissue.
• There were multifocal areas, or multiple sites of necrosis, i.e., severe cell injury leading to cell death inside the tumor
• The tumor cells tested positive, showing a strong reaction to alkaline phosphatase, an important enzyme often found in the human body.
• An immunohistochemical examination was performed to understand the nature and function of the cells better, which expressed vimentin, a protein that supports cellular integrity and is negative for cytokeratin, a type of protein generally found in the intracytoplasmic cytoskeleton of epithelium tissue, indicating the lack of such tissues.
• An ultrastructural study found that the cancer cells had an elaborate reticular nucleolonema in an irregular configuration, a feature that is often associated with intense ribosomal biosynthesis and increased metabolic activity, common in proliferating cells such as cancerous cells.

Conclusion

The article constitutes a significant addition to the limited knowledge available on dysgerminoma, a rare germ cell tumor of the ovary in horses. It provides extensive details derived from this particular case, using various microscopic examinations such as histology, immunohistochemistry, and ultrastructural study. The study hopes to deepen understanding of this rare type of tumour in horses and provide a useful resource for future investigations.