Radiotherapy of a recurrent ossifying fibroma in the paranasal sinuses of a horse.

This study reports on a case of a horse suffering from a recurring ossifying fibroma in the paranasal sinuses. The researchers found that using radiotherapy as an adjunctive treatment after surgical removal of the tumor could delay or prevent the tumor’s return.

Introduction

• This research focuses on the treatment of a recurrent ossifying fibroma, a rare tumor, in a Thoroughbred horse.
• The 7-year-old female horse presented symptoms like labored breathing, stridor (high-pitched squeaking sound due to obstructed air flow), and intolerance to exercise, leading to its referral to a veterinary clinic.
• An examination revealed the presence of a mass in her left paranasal sinuses, identified to be an ossifying fibroma – a benign tumor generally originating from the bones that often recur if not fully removed.

Treatment and Results

• The initial treatment approach was conservative, involving only surgical removal of the mass. However, the tumor recurred after 9 months.
• Upon recurrence, the mass was surgically removed once more, but this time, it was followed by adjunctive radiotherapy involving 3,000 cGy of cobalt radiation. This combination of treatments yielded improved results – the tumor did not resurface for over 6 years.
• After this period, the fibroma reappeared. The veterinary team performed a third surgery to remove the tumour, followed by an increased dosage of adjunctive radiotherapy – 4,000 cGy of photon beam radiation from a linear accelerator. This approach held off the tumor’s recurrence during the subsequent 3 years.

Conclusions

• This case study suggests that combining surgical tumor removal with adjunctive radiotherapy can yield more effective, lasting results in treating ossifying fibromas in horses.
• The radiotherapy doses administered following surgery appeared to significantly delay – and in the latter case, even prevent – tumor recurrence.
• The findings could be useful in managing similar cases in the future, although more studies are likely needed to validate these results and determine the optimal radiation dose.