Diverticulum-like Adenomyosis on the Cesarean Scars of the Uterus: A Rare Type of Cystic Adenomyosis

A 43-year-old woman was admitted to the hospital with prolonged menstruation after cesarean delivery for 14 years and intermenstrual bleeding for half a year. Magnetic resonance imaging and ultrasonography revealed a mass of 3.3 cm in diameter located on the left uterine isthmus, connected to the uterine cavity (Fig. 1). The cesarean scar defect was explored by hysteroscopy, and a diverticulum with viscous chocolate-like fluid inside was found on the left wall of the cesarean scar defect (Fig. 2A). A methylene blue staining solution was administered into the mass under laparoscopy, and blue fluid gushed out into the uterine cavity as observed under hysteroscopy. The mass was exposed (Fig. 2B) and excised (Fig. 2C). Wound repair was performed using laparoscopic sutures. The thick-walled mass (Fig. 2D) contained endometrium-like tissue in the inner wall and chocolate-like fluid inside. The pathologic examination revealed that the mass consisted of the endometrial glandular epithelium and hyperplastic smooth muscle, verifying cystic adenomyosis (Fig. 3). The patient's menstrual condition returned to normal after the surgical procedure.Fig. 2(A) An opening of 1.0 cm in diameter on the left wall of the cesarean scar defect was found with viscous chocolate-like fluid inside under hysteroscopy. (B) The mass of 3.3 cm in diameter was located on the left uterine isthmus (blue arrows). (C) The mass was removed after dissecting the vesicouterine fold of the peritoneum under laparoscopy. (D) The excised lesion had chocolate-like fluid inside with thick wall.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. 3The pathologic photomicrograph of the cystic adenomyosis: endometrial glandular epithelium (green arrows) and hyperplastic smooth muscle (yellow arrows) were shown. Hematoxylin and eosin staining, × 100.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Cystic adenomyosis is an uncommon variant of adenomyosis characterized by a circumscribed cavitated endometrial gland and stroma placed within the myometrium. Different from typical cystic adenomyosis, characterized by lesions independent of the normal endometrium cavity [1Fan YY Liu YN Li J Fu Y. Intrauterine cystic adenomyosis: report of two cases.World J Clin Cases. 2019; 7: 676-683Crossref PubMed Scopus (8) Google Scholar], this specific type of adenomyosis, so-called "diverticulum-like adenomyosis," is connected to the uterine cavity without dysmenorrhea. However, it might result in increased menstruation and abnormal uterine bleeding. The rare case has never been reported before. Early identification and surgical treatment could timely alleviate menorrhagia, anemia, and other symptoms. Moreover, the current case supported the hypothesis of endometrial invagination caused by the surgical injury in the development of adenomyosis [2García-Solares J Donnez J Donnez O Dolmans MM. Pathogenesis of uterine adenomyosis: invagination or metaplasia?.Fertil Steril. 2018; 109: 371-379Abstract Full Text Full Text PDF PubMed Scopus (122) Google Scholar]. The authors thank Lei Pan, Yurong Jiao, Wenwen Wang, Kui Li, and Wenjie Huang who aided in the data collection and image production.