Uterine serosal inclusion cysts in a cat

CASE REPORT: A 7-year-old, clinically well, pluriparous queen was presented for routine ovariohysterectomy. Laparotomy revealed multiple thin-walled cysts of various sizes over a large portion of the uterine body and both uterine horns. Histopathological examination confirmed the presence of cysts arising from the uterine serosal surface. The cysts were lined by cuboidal cells consistent with mesothelial cells, based on immunohistochemical staining patterns. Based on the location and morphology of the cysts, a diagnosis of uterine serosal inclusion cysts was made. CLINICAL SIGNIFICANCE: Uterine serosal inclusion cysts are rare in cats, having only been reported in the literature once previously. This is the first reported study in a cat where immunohistochemical stains suggest the cystic lining to be mesothelial in origin. In animals, uterine serosal inclusion cysts are not thought to cause any reproductive dysfunction and should remain a differential diagnosis in cases of intraabdominal cystic abnormalities.