RESUMO
Background: Cystic endometrial hyperplasia is a hormone-dependent disease induced by systemic increase in progesteronethat can occur in several domestic species, such as the rabbit. This disease may be associated with sex steroid hormones,especially progesterone, and may be asymptomatic, and it is diagnosed using complementary imaging tests such as totalabdominal ultrasound. However, surgical excisional biopsy with histopathological tissue analysis is the gold standard. Thisstudy reports a case of asymptomatic cystic endometrial hyperplasia in a female Miniature Lion Lop rabbit (Oryctolaguscuniculus domesticus) treated with therapeutic ovariohysterectomy.Case: A domestic, adult, female Miniature Lion Lop rabbit (Oryctolagus cuniculus domesticus), aged approximately 5 yearsand weighing 3.2 kg, was referred to specialized care to undergo ovariohysterectomy, an elective procedure. The tutor onlyreported the occurrence of a single episode of vulvar secretion more than 2 years ago, treated with antibiotics, with remissionof clinical signs. In the intraoperative period after celiotomy, the uterine horn and uterine body showed a significant increasein volume, with abnormal color changes and tissue consistency; however, both changes were clinically asymptomatic. Subsequently, biopsy was performed during the ovariohysterectomy procedure. The excised uterus and ovaries were placed in 10%formalin and histopathologically analyzed. The macroscopic histopathological examination of the sectioned tissue revealed aslight amount of brownish fluid inside the uterine horns, in addition to multiple cystic areas in the uterine mucosa. Microscopicexamination revealed marked hyperplasia of well-differentiated endometrial epithelial cells, occasionally forming cystic structuresof different sizes. Moderate congestion, mild multifocal hemorrhage, and mild multifocal inflammatory infiltrate in the lamina...