Cisto branquial em papagaio-verdadeiro (<i>Amazona aestiva</i>):

Branchial cyst is a congenital neoplasm caused by the bad obliteration of one of the branchial slits during embryonic development, presenting benign cells and which will manifest itself throughout the individual's lifetime, damaging lateralized structures such as vessels, arteries, nerves, and the pharynx as well as a result of compression due to the increase in volume. In this report, a 32-year-old male blue-fronted parrot (Amazona aestiva) will be presented, which highlighted a floating and soft right lateral cervical neoplasia measuring 11 cm that had developed over about a month, showing no signs of pain, but discomfort, despite the size of the mass, and normal food and water intake, being able to perform behaviors such as maintaining feathers and rotating its head along with usual activities. With the results of the radiography, exclusively surgical treatment began. With the excision of the neoplasm and histopathological analysis, a branchial cyst was determined, with the presence of fibrous tissues, columnar and pseudostratified areas, the patient receiving supportive medication such as dipyrone, maxican and tramadol shortly after. This work aims to cover the dimension of this anomaly, its diagnosis and treatment, also serving as an aid for possible differential diagnoses.