A 12-year-old castrated male Quarter Horse was examined because of a puncture wound over the left maxillary sinus ventral to the facial crest. Left nasal epistaxis was noticed the morning of the examination. Physical and oral examinations revealed that the horse also had a firm, movable mass that communicated with the oral cavity. The mass was rostral to the puncture wound. Signs of pain were not elicited during examination. The owner reported that the mass had been evident for approximately 10 years. Digital radiographic images of the skull were obtained (Figure 1).