Use of Ir192 interstitial brachytherapy for an equine malignant dermal schwannoma.

The research discusses a procedure where wires coated in a platinum mixture were successfully used to treat a horse with an aggressive, recurring tumor, suggesting this method could be used for other cases where surgery is not an option.

Case Context

• The research focuses on the treatment of a malignant dermal schwannoma (a rare type of cancer derived from the peripheral nerve sheath cells) that occurred to a 10-year-old Hanoverian mare. The tumor was located in the right buccal area (the cheek) and had recurred three months after initial surgical removal.

Treatment Method

• Using ultrasound, the team identified a large, pedunculated (attached by a stem-like structure) subcutaneous mass associated with an erosive cheek lining lesion.
• Upon confirming the diagnosis through biopsy, the team utilized a treatment method called interstitial brachytherapy. This involves placing radioactive substances (in this case, platinum-coated Ir192 wires) inside or next to the affected area, providing a low dose radiation treatment.
• In this specific case, the horse was put under general anesthesia and received a dose of 5 gray (unit of absorbed radiation dose) per day for 14 days.

Short-term Complications and Recurrence Rate

• Though the treatment resulted in some short-term complications, such as dermatitis, erythema (skin redness), leukotrichia (whitening of hair), a blocked right nasolacrimal duct (tear duct), and left-sided deviation of the muzzle, the tumor did not return even 10 months after the therapy.
• These results suggest that interstitial brachytherapy could be an effective treatment method for malignant dermal schwannomas, especially when surgery is not possible or when the tumor recurs following surgery.