Intralesional administration of formalin for treatment of epidermal inclusion cysts in five horses.

The research article reveals the effectiveness of using formalin, injected directly into the cyst, as a treatment for epidermal inclusion cysts in horses, found in their nasal diverticula.

Objective and Procedure

• The study was carried out on five horses that had unilateral epidermal inclusion cysts located in the nasal diverticula.
• Each horse was provided with anaesthesia, and then the neutral-buffered formalin (10% concentration) was directly injected into the cyst. The volume of formalin injected ranged between 2 to 4.5 mL. This is known as intralesional injection.
• This injection was performed until leakage of fluid around the needle was observed, indicating that the cyst was having enough of the formalin.

Follow-ups and Treatment Results

• In the weeks following the treatment, the drying up or desiccation of the cyst was noticed.
• Two weeks after the treatment, the cyst was surgically removed in three of the horses.
• In one horse, the owner manually removed the cyst, and in another horse, the cyst was never removed as the owner denied further treatment after seeing the resolution of the initial swelling of the nasal diverticulum.
• All horses experienced swelling of the cyst after the treatment. Additionally, only some experienced nasal discharge (2 horses) and a mild instance of nosebleed or epistaxis (1 horse).

Conclusion

• In conclusion, the use of intralesional administration of formalin proved to be a simple and efficient therapy for treating epidermal inclusion cysts in horses’ nasal diverticula.
• Even though some minor complications like cyst swelling, nasal discharge and mild nosebleed were identified, the primary objective of cyst treatment was successfully achieved.