Pregnancy-related decidualization in post-cesarean section scar endometriosis: A case report

Introduction and importance: Post-cesarean section decidualized endometriosis is a rare phenomenon where ectopic endometrial cells undergo changes, such as atypia, under the influence of high progesterone levels at the site of cesarean section. This phenomenon can create a diagnostic challenge as it mimics the characteristics of malignancy to some extent. Case presentation: We report a case of a 38-year-old G6P2 woman who was electively referred to the OB ward for a cesarean section. Ultrasonography revealed a 38 x 29 x 26 mm lobulated solid lesion within the rectus abdominis muscle located in the midline of the suprapubic abdominal wall in the 16th week of gestation. Histological evaluation of the specimen showed endometrial glands surrounded by severely decidualized stroma. Clinical discussion: To our knowledge, we present the ninth case report of decidualized endometriosis located on a post-cesarean section scar. Our case was in the younger demographics and histopathologically her resected tissue contained glandular structures. There was no past medical history of endometriosis. Extra pelvic localization of the tissue could have led us to a diagnostic pitfall. Conclusion: Understanding this phenomenon's pathologic and clinical characteristics can help pathologists and surgeons to rule out malignancy and avoid conspicuous diagnostic errors.