Cystic Rete Ovarii and Uterine Tube Adenoma in a Rabbit

A 6-year-old female rabbit was presented to a veterinary clinic, and the result of ultrasound examination suggested a tumor in the uterine tube. Subsequently, both ovaries and uterus were surgically removed. In gross, a single large cyst in the right ovary and enlargement of the left uterine tube were observed. Histological examination revealed that the cyst had developed in the hilus of the ovary and was lined by single-layered cuboidal cells. In the left uterine tube, a tumor composed of epithelial cells arranged in tubular structures and pleomorphic cells between the tubular structures was observed. Immunohistochemically, the epithelial cells of the cyst were positive for pan-cytokeratin, cytokeratin 18, CD10, E-cadherin, calretinin and estrogen receptor; the tumor cells of the left uterine tube were positive for pan-cytokeratin, cytokeratin 18, E-cadherin, vimentin, calretinin and estrogen receptor. From these results, the cyst was diagnosed as cystic rete ovarii, and the tumor was diagnosed as adenoma of the uterine tube. This case is the first to demonstrate cystic rete ovarii and uterine tube adenoma in rabbits.