Chondromas on the medial surface of the arytenoids are not a very common finding in upper respiratory syndromes found in horses. They can be caused by abnormal turbulence in the upper airway for passage of air and subsequently cause poor performance in horses.
It is usually secondary to another pathology in the upper airway (like the DDSP) that cause turbulence of air between the arytenoids and stimulate the cartilage to grow abnormally.

The optimal treatment is using laser technology because it causes tissue to evaporate and allows a lower percentage of granulation tissue to fill the lesion.

This horse had an ulcer on the soft palate that was displaced as well (DDSP). The ulcer was due to the permanent displacement of the soft palate and the abnormal air flow on the tip of the palate.