Amir Asghari Baghkheirati - Department of Avian Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Sara Shokrpoor - Department of Pathology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Mohammad Hassanzadeh - Department of Avian Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Javad Javid Nezhad - Department of Avian Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
Jamshid Razmyar - Department of Avian Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.

Budgerigar (Melopsittacus undulatus) is a tiny colorful parrot and one of the most popular pets worldwide. This study was performed on a ۵-year-old male budgerigar with a large and fluid-filled mass in the anterior part of the neck. Fine needle aspiration was accomplished to determine tumor origin, and the tumor content was cultured on blood and MacConkey agars (aerobic and anaerobic conditions). Besides, tumor ultrasonography and whole-body radiographs were done in the lateral and ventrodorsal positions. Finally, the tumor was removed, fixed in ۱۰% neutral buffered formalin, and stained with hematoxylin and eosin (H & E). The radiology and ultrasonography results showed that the tumor (۵.۲×۴×۳.۷ cm) had a homogenous structure filled with echogenic fluid content. The tumor content culture revealed no bacterial growth. Histopathologically, the mass was composed of cystic spaces with invagination of the lining epithelial cells, forming intraluminal papillae. The tumor was diagnosed as a papillary cystadenocarcinoma.

budgerigar, Cystadenocarcinoma, Histopathology, Radiology, Ultrasonography