Paranasal Sinus Cyst in a Horse

Figure 1A

Figure 1B

The radiographs in Figure 1-3 correspond to a horse that presented for chronic nasal discharge. The discharge was bilateral and there was a reduction in the air flow through the nasal passages. Due to the reduced airflow, it was decided to first radiograph the gelding's skull and then potentially scope the upper airway.

Figure 2A

Figure 2B

Radiographic exam revealed a soft tissue mass that was located in the maxillary sinus. In Figures 1-2 A and B the soft tissue mass appears as a round, white structure that is highlighted by the red dotted circles. In Figure 3 there appears to be a soft tissue mass in both the left and right maxillary sinus (red dotted circles). The mass appears larger on the left side of the skull.
The gelding was NOT sedated for endoscopic exam in order to reduce the likelihood of respiratory distress.

Figure 3

 In Figure 4, an endoscopic image reveals a smooth, soft tissue tumor/mass that is obstructing the nasal passage. Moderate amounts of purulent debris can be seen accumulating around the soft tissue mass. Based on the endoscopic and radiographic findings, the gelding was referred for surgical exploration. At surgery, a large paranasal cyst was exposed in the left maxillary sinus and a small cyst was identified in the right maxillary sinus. Both cysts were removed and the gelding recovered uneventfully. It is likely that the cysts began to develop early in life for this gelding and did not become clinically relevant until they grew into the nasal passages. Once they are removed via surgical intervention the prognosis is very good !!

Figure 4