Periocular basal cell carcinoma in a donkey: case report.

This research article describes a case of a 10-year-old donkey with a rare instance of basal cell carcinoma, a type of skin cancer, found in its eye region. The paper details the clinical presentation, diagnosis, treatment, and pathological examination. Although such tumor type is uncommon in horses and donkeys, this report emphasizes the importance of including it in differential diagnoses of periocular tumors in these animals.

Clinical Presentation

• The donkey in this case exhibited good health condition except for a new growth identified in its right eye, which was noticed 3 months before the animal was admitted to the hospital.
• The eye tumor was located above and adhered to the cornea, and its size measured 3.0 x 2.5 x 1.5 cm.

Diagnosis

• Cytology, a type of test that examines cells, raised a suspicion of a malignant epithelial neoplasm due to groups of cohesive cells displaying a palisade arrangement occasionally.

Treatment

• Although the tumor excision associated with chemotherapy was recommended, the owner did not approve it due to financial constraints, accepting the higher risk of recurrence.
• Instead, the exenteration of the globe, a surgical procedure to remove the eye that contains the tumor, was chosen.
• The procedure was performed under general anesthesia, executed without complications and with an appropriate surgical margin.

Pathological Examination

• The tumor was non-encapsulated and infiltrative, supported by thin fibrovascular stroma and organized into islands and nests.
• Cells in the tumor were polygonal, had indistinct borders, had a round to oval nucleus with a single, large nucleolus, and contained an eosinophilic, or acid-loving, substance in their spaces.
• An immunohistochemistry test revealed that the tumor was positive for pan-cytokeratin, a type of keratin found in all epithelial cells, and negative for vimentin, Sox-10 and Melan-A, proteins generally associated with certain types of tumors.

Follow-Up

• 12 months after the surgical excision, there was no report of recurrence or complications.

Conclusion

• This report highlighted that although rare, basal cell carcinoma can occur in the periocular region of horses and donkeys and should be included in differential diagnoses of tumors in these areas.