CYP19A1 and endometriosis: Noble et al. (1996) demonstrated aromatase expression in both the eutopic endometria and ectopic lesions of endometriosis patients, whereas normal endometrial and nondiseased peritoneal tissues lacked detectable aromatase. Malik et al. (2018) performed immunohistochemical analysis of menstrual blood samples from endometriosis patients and nonendometriosis patients.