Aim of this paper is to report the first case of a feline cystic adrenocortical tumor. A 9-year-old, castrated male shorthair cat was referred for an abdominal mass accidentally palpated by the owner. Ultrasound showed a large inhomogeneous cystic mass close to the left kidney. A massive ablation of the mass was performed. Four days after surgery, the cat was severely azotemic and presented signs of multiple organ dysfunction. The cat was euthanized the 7^th day after surgery. Histopathological examination was consistent for adrenocortical serous cystadenoma.

Key words: Adenoma, Adrenal gland, Cat