Congenital Osteoma of the Frontal Bone in an Arabian Filly

Congenital frontal osteoma has not been previously described in horses. This report records-for the first time-a congenital osteoma of the frontal bone in a 4-month-old Arabian filly. The filly had a frontal hard mass that was present at birth and then showed a slow and continuous growth. This mass appeared as a solitary, painless, oval dense tumor of compact bone, about 2 cm in diameter and 3 cm in length. The tumor was asymptomatic, and the skin over the mass was normal. Radiography revealed a well-defined oval, radio-dense mass projecting from the surface of the right frontal bone with no local invasion. The tumor had a broad-based attachment to frontal bone with normal frontal sinus. The mass caused disfigurement; therefore, it was removed at the owner's request. The mass was diagnosed histopathologically as osteoma. The surgical excision of the osteoma was successful without any complications, and the filly adapted remarkably well after surgery. No recurrence was reported 20 months after the surgery. In conclusion, osteoma should be listed during the differential diagnosis of the congenital craniofacial masses in horses. Early diagnosis of the frontal osteoma guarantees a successful surgical treatment and consequently prevents the future complications.