Bilateral intraocular glandular choristomas in a Thoroughbred foal.

This research paper discusses a case of a Thoroughbred foal diagnosed with intraocular glandular choristomas, a rare eye condition in domestic animals that is often associated with multiple eye abnormalities. The study further examines the morphological, histochemical, and immunohistochemical comparisons between ocular choristomatous tissues in the foal and selected parts of normal horses. The findings suggest the lacrimal sac likely being the origin of intraocular glandular choristomas in this case.

Comprehensive Case Overview

• The Thoroughbred foal was examined after presenting for ocular, or eye, abnormalities. Diagnosis revealed a condition called intraocular choristomas which are rare abnormalities within the eye found in domestic animals.
• Alongside this, the foal was diagnosed with multiple other ocular disorders. These included microphthalmia (abnormally small eyes), corneal dermoids (a type of benign tumor), severe anterior segment dysgenesis (abnormal development of the front segment of the eye), aphakia (the absence of an eye’s lens), retinal dysplasia (abnormal development of the retina), and optic nerve hypoplasia (underdevelopment of the optic nerve).

Morphological, Histochemical, and Immunohistochemical Comparisons

• The researchers carried out morphological, histochemical, and immunohistochemical comparisons between the affected foal’s ocular choristomatous tissues and lacrimal gland, third eyelid gland, nasopharynx, trachea, and lacrimal sac/nasolacrimal duct from healthy horses.
• Morphologically, researchers noted that the choristomatous tissues (which include the glands and epithelium lining the anterior segment) exhibited significant similarities with the lacrimal sac, providing an initial hint regarding the likely origin of the choristomas.
• The histochemical evaluation of glandular components of these tissues revealed that the glands associated with the lacrimal sac/nasolacrimal duct, along with the glandular intraocular choristomas, were serous or watery, further supporting the conclusion drawn from the morphological similarities.

Conclusions

• Based on these findings, the researchers suggested that the intraocular glandular choristomas in this particular case may have originated from the lacrimal sac.
• This important insight could provide valuable information for further understanding and treating similar ocular conditions in animals, particularly horses.