Peer-reviewed veterinary case report
Unilateral choristoma of the nictitating membrane in a horse.
- Journal:
- Journal of the American Veterinary Medical Association
- Year:
- 2015
- Authors:
- Gornik, Kara R et al.
- Affiliation:
- Department of Clinical Sciences · United States
- Species:
- horse
Plain-English summary
A 2-year-old Morgan mare was seen by a veterinarian because she had a sore on her cornea, which is the clear front part of the eye. During the exam, the vet found an unusual deep ulcer in her left eye and noticed that the nictitating membrane, a small fold of tissue in the eye, had hairs growing from it that were touching the cornea. The mare underwent surgery while under general anesthesia, where the vet removed the abnormal tissue and hair follicles from the nictitating membrane. After six weeks, the mare showed no signs of discomfort, the hairs did not grow back, and she did not have any vision problems. Overall, the treatment was successful.
Abstract
CASE DESCRIPTION: A 2-year-old Morgan mare was evaluated because of a corneal ulceration. CLINICAL FINDINGS: An irregular, deep stromal corneal ulcer in an area of malacia was noted in the left eye. Hypopyon was present in the ventral portion of the anterior chamber with moderate aqueous flare. The nictitating membrane of the left eye had hairs originating from its leading edge that contacted the corneal surface. TREATMENT AND OUTCOME: General anesthesia was induced, and a bulbar pedicle conjunctival graft was performed. The conjunctiva at the leading edge of the nictitating membrane, including the aberrant hair follicles, was excised. Microscopically, a nonkeratinized stratified squamous epithelium, sebaceous glands, and hair shafts were present, confirming a choristoma of pilosebaceous origin at the leading edge of the nictitating membrane. Six weeks after surgery, the horse had no signs of discomfort, with no regrowth of the hairs; no loss of vision was evident. CLINICAL RELEVANCE: Ocular choristomas develop secondary to defective fetal cellular differentiation and are rarely reported in the equine literature. The choristoma in this horse contained ectopic hair follicles with hair growth as well as sebaceous glands. This finding emphasizes the importance of a thorough adnexal examination in horses with corneal disease.
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Search related cases →Original publication: https://pubmed.ncbi.nlm.nih.gov/25554940/