Narz, an 8 year old Warmblood gelding presented to Cornell on 6/12/08 for peripheral vestibular signs and a presumptive guttural pouch mycosis. Cytology and culture of the guttural pouch plaque confirmed the presence of Aspergillus fumigatus. A CT was performed that demonstrated an infiltrative soft tissue mass in the left guttural pouch and temporal region. A left common carotid artery ligation was performed and Narz was treated post-operatively with intravenous sodium iodide, oral potassium iodide, and topical nystatin powder. The fungal plaque resolved by 7/15/08 and his neurologic signs improved. On 7/15/08, a mass was palpated at the base of his thoracic inlet and a biopsy revealed carcinoma. Narz was euthanized due to the poor prognosis of metastatic squamous cell carcinoma. This case will be used to demonstrate the etiology, pathophysiology, diagnostics and treatment of guttural pouch mycosis and will illustrate why this was an atypical presentation.