Surgical Treatment of Corneal Large Dermoid in a Simmental Calf

Background: Ocular dermoid is a skin or skin-like appendage usually arising on the limbus, conjunctivae, and cornea. It can be unilateral or bilateral and may be associated with other ocular manifestation or with other malformations. Hair from the lesions is predominantly responsible for the associated irritation resulting in chronic inflammation of the conjunctivae and cornea and may cause visual impairment. Ocular dermoids are rare in cattle, with the prevalence estimated between 0.002% and 0. 4%. Case: A one-day-old Simmental calf presented for bilateral haired masses on the eyes and tumor-like growth since birth. The calf was admitted to the University of Adnan Menderes, Faculty of Veterinary Medicine 1 days after initial examination. The calf weighed 35 kg, was in good bodily condition and no further abnormalities were detected on physical examination, complete blood count and serum chemistries. General anesthesia was induced and maintained with an intravenous detomidine-ketamine-midazolam combination. The corneal dermoids extended slightly beyond the inferonasal limbus and then merged with a second mass of lightly haired tissue within the inferonasal bulbar conjunctiva of both eyes. The dermoids were excised by superficial lamellar keratectomy that was extended into the inferonasal conjunctiva. The nasal masses were excised by electrocautery. All excised tissue was submitted for histopathology. Histopathology of the excised tissue confirmed bilateral corneoconjunctival dermoids with bilateral nasal hyperplastic tissue. Topical 1% atropine sulfate ointment was applied twice daily to both eyes for 5 days and bacitracin-neomycin-polymixin ophthalmic ointment applied twice daily to both eyes for 2 weeks postoperatively. Ocular and nasal healing was uneventful, with prominent corneoconjunctival granulation tissue 6 days postoperatively, which largely resolved by the 6-week follow-up examination. Bilateral large dermoids with nasal hyperplastic tissue have not been documented previously in Simmental cattle in Turkey. Discussion: The precise developmental mechanisms involved in the pathogenesis of ocular dermoids are not known. Metaplasia of mesenchyme (of primarily neural crest origin), resulting in abnormal differentiation of the surface ectoderm, is considered the most likely mechanism. Ocular dermoids may be associated with other congenital ocular or multiorgan abnormalities. The medial and lateral nasal processes, optic vesicle and first and second branchial arches are in close relationship on the lateral side of the embryonic head and might all be adversely influenced by the same stimulus. Ectopic lacrimal tissue may appear in combination with an ocular dermoid as in this case report and previously reported in cattle, or alone as an epibulbar choristoma. The ectopic lacrimal tissue in this calf may have represented misplacement of the nictitans gland or additional lacrimal tissue development. Superficial keratectomy is required to surgically excise a corneal dermoid although the depth of the dermoid within the cornea cannot be ascertained by ophthalmic examination until surgery is undertaken. In the case of large corneal dermoids, surgical excision should be performed early in the life of the patient to achieve optical improvement and allow functional development of the eye.