Adenomyosis in a domestic feline: a case report

Adenomyosis is a non-neoplastic condition which affects the female reproductive system. This condition is rare in domestic animals, and is characterized by the invasion and abnormal growth of the endometrium into the uterine muscle region. Herein, we describe the histopathological findings of uterine adenomyosis with delayed diagnosis in a three-year-old domestic female cat, of undefined breed, with a history of periodic administration of exogenous progestagens. The cat underwent ovariohysterectomy, during which macroscopic incidental changes of increased volume in the left uterine horn were observed. Microscopic analysis further revealed marked glandular epithelial hyperplasia in the endometrium, along with multiple cystic areas composed of well-differentiated columnar epithelial cells, mild multifocal hemorrhage, and deposition of amphophilic amorphous material. Some glandular structures and cystic dilations were noted in the myometrium. Based on histopathological findings, a diagnosis of cystic endometrial hyperplasia with endometritis and adenomyosis was made. Despite the delayed diagnosis, surgical treatment proved effective in this case.