A novel and rare diverticulum-like adenomyosis: A case report

A 42-year-old asymptomatic woman with a history of two cesarean sections visited the Obstetrics and Gynecology Clinic of our hospital due to an unexpected discovery of a parauterine cyst on abdominal computed tomography, which was used to diagnose urinary tract diseases ( Fig .1 ). Gynecological examination revealed a lump in the left front of the uterus, about the size of a fist, fixed, and without tenderness. The initial diagnosis was an ovarian cyst, but before admission, an ultrasound showed an “ovarian endometriosis cyst” ( Fig. 1 b). After further MRI, we discovered that the cystic lesion, measuring 7.6 × 6.1 × 7.7 cm, was located on the scar of the uterus and communicated with the uterine cavity through a very small channel ( Fig. 1 c). The fluid in the cyst showed high signal intensity on T1-weighted image (T1WI) and the surrounding cyst wall showed a marked low signal intensity on T2-weighted image (T2WI), with no apparent masses found on either side. The serum CA125 level was 36.6 U/ml, the hemoglobin level was 133 g/l, and the liver and kidney functions were normal. Based on the patient's medical history and MRI results, we provided various treatment options, including hysteroscopic and laparoscopic surgery, and explained the benefits and risks. After obtaining informed consent, an experienced chief physician performed a laparoscopic exploration. Intraoperatively, it was found that the cystic mass of 7.6 ∗ 6.1 ∗ 7.7 cm was located on the left uterine isthmus ( Fig. 2 ), and the excised lesion contained chocolate-like fluid inside with thick walls ( Fig. 2 b). After removing the cyst wall completely, the cyst cavity was sealed with absorbable sutures. Pathological examination revealed typical endometrial glands and interstitial tissues in the cystic wall, along with smooth muscle tissue proliferation ( Fig. 3 ). This confirms a new type of diverticulum-like cystic adenomyosis of the uterus. One month later, the patient came for a follow-up examination, and computed tomography showed that the mass had disappeared ( Fig. 1 d). The patient had a normal menstrual period, and no other abnormalities were reported. Fig. 1 a Computed tomography showed a parauterine cyst; 1b Ultrasound showed that the mass was an ovarian endometriotic cyst; 1c Magnetic resonance imaging showed the opening of a mass in the uterine cavity; (d) One Month After Surgery under CT. Fig. 1 Fig. 2 a The mass of 7.6 cm in diameter was located on the left uterine isthmus; 2b The excised lesion had chocolate-like fluid inside with thick wall. Fig. 2 Fig. 3 The pathologic photomicrograph of the cystic adenomyosis: endometrial glandular epithelium and hyperplastic smooth muscle were shown. Hematoxylin and eosin staining, £ 100. Fig. 3 a Computed tomography showed a parauterine cyst; 1b Ultrasound showed that the mass was an ovarian endometriotic cyst; 1c Magnetic resonance imaging showed the opening of a mass in the uterine cavity; (d) One Month After Surgery under CT. a The mass of 7.6 cm in diameter was located on the left uterine isthmus; 2b The excised lesion had chocolate-like fluid inside with thick wall. The pathologic photomicrograph of the cystic adenomyosis: endometrial glandular epithelium and hyperplastic smooth muscle were shown. Hematoxylin and eosin staining, £ 100.

Yali Cheng, Yihong Pan: Managed the patient and played the surgery, Weibo Li: design of the study, provided imaging data, Yanyun Liu: wrote, revision the manuscript.

We obtained written informed consent from the patient to publish this case report, along with accompanying images. A copy of the written consent is available upon request for review by the Editor-in-Chief of this journal.

Our institution does not have any specific ethical requirements for the publication of case reports. Since this report pertains to a single case, it is exempt from ethical review in our hospital.

This work was supported by the Taizhou shi ke ji ju , Project No 20ywa14.

Yanyun Liu and Yihong Pan.

Diverticulum-like adenomyosis is a rare form of cystic adenomyosis that is not frequently reported in the medical literature. Due to it is uncommon nature, the diagnosis of this condition can be challenging and often leads to misdiagnosis.

Cystic adenomyosis is a benign and rare disease found in women of reproductive age that is known to cause symptoms such as heavy menstrual bleeding, dysmenorrhea, and abnormal uterine bleeding [ 7 ]. Radiographically, cystic adenomyosis appears as lytic solitary or multifocal cystic foci independent of the endometrial cavity. Histologically, it is defined as the presence of endometrial glands and stroma in the cyst wall. It is essential to differentiate cystic adenomyosis from ovarian cysts and congenital uterine malformations [ 2 , 4 ]. Our case was initially misdiagnosed as an ovarian cyst on ultrasound examination. The most widely accepted pathological mechanism for cystic adenomyosis is the invagination of the basalis endometrium into the myometrium [ 4 ]. Laparoscopic lesion resection is an effective treatment for cystic adenomyosis due to the advantages of minimal trauma, clear vision, and fast recovery, as reported in most studies [ [8] , [9] , [10] ]. Diverticulum-like Adenomyosis is a rare and novel form of cystic adenomyosis. The first case was reported by Xinyun Yang et al. in a 42-year-old woman with abnormal uterine bleeding [ 5 ]. Our report represents only the second documented case of diverticulum-like adenomyosis. However, our patient did not experience abnormal uterine bleeding or dysmenorrhea, possibly due to the small size of the sinus tract that prevented blood influx into the uterine cavity. However, we did not perform hysteroscopic exploration to determine the exact reason for the absence of abnormal uterine bleeding. Additionally, the lesion is independent of the uterine corpus and does not interfere with uterine smooth muscle contractions, which could otherwise result in dysmenorrhea.

Adenomyosis is a benign uterine disease characterized by the presence of ectopic endometrial glands and stroma in the myometrium, along with adjacent smooth muscle hyperplasia [ 1 ]. The exact pathogenesis of adenomyosis is poorly understood. Still, the most widely accepted mechanism is a deep invasion of the inner myometrium by eutopic endometrium, which disrupts the endometrial-myometrial interface (EMI). When a cyst is filled with ectopic endometrial tissue and blood exceeds 1 cm in size, it is called cystic adenomyosis or cystic adenomyoma [ 2 , 3 ]. Cystic adenomyosis is a rare entity, first reported in 1908, and is more commonly encountered in younger patients [ 4 ]. Most case reports of cystic adenomyosis show that the lesions are located in the uterine muscular wall or subserosa. Diverticulum-like adenomyosis is an even rarer type of adenomyosis, with only one case reported so far [ 5 ]. Our case report presents a 42-year-old asymptomatic patient with diverticulum-like adenomyosis and is reported according to the Surgical Case Report (SCARE) criteria [ 6 ].

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The authors declare that they have no conflicts of interest.