Gastrointestinal stromal tumors in equids

Area of Science:

• Veterinary Pathology
• Equine Neoplasia
• Gastrointestinal Oncology

Background:

• Gastrointestinal stromal tumors (GIST) are recognized in humans, dogs, and nonhuman primates.
• Equine GIST have not been extensively documented, necessitating further investigation.

Purpose of the Study:

• To characterize the clinicopathologic, histopathologic, immunohistochemical, and ultrastructural features of equine gastrointestinal neoplasms.
• To determine the cell of origin and potential diagnostic markers for these equine tumors.

Main Methods:

• Gross, histological, and immunohistochemical examination of eleven equine gastrointestinal neoplasms.
• Ultrastructural analysis of two selected tumors.
• Evaluation of clinical signs and incidental findings.

Main Results:

• Eleven GIST were identified in horses and ponies, located in the stomach, jejunum, ileum, cecum, and colon.
• Neoplasms displayed spindle cell morphology with vimentin positivity in all cases; S-100 and muscle actin were positive in a subset.
• Ultrastructural findings suggested a mixed myogenic and neurogenic or undifferentiated mesenchymal origin.

Conclusions:

• This study confirms equids as a newly recognized species affected by GIST.
• Equine GIST exhibit diverse histological and immunohistochemical features, similar to those in other species.
• Further research is warranted to elucidate the specific cell lineage and pathogenesis of equine GIST.