Adenomyosis is a common benign gynecologic disease characterized by invasion of the endometrial matrix or glands into the myometrium [1]. The disease may be focal or diffuse [2] and may appear as small cystic spaces, usually 5 mm in diameter, containing a small amount of old blood [3]. When the fused or single lumen of the cystic space has a diameter greater than or equal to 1 cm, the condition is called cystic adenomyosis (CA) [4]. CA is a special type of focal adenomyosis, also called cystic adenomyoma or adenomyotic cyst. Its main clinical manifestation is dysmenorrhea and is most commonly found in younger women (under the age of 30) who have no history of uterine surgery [5].

Consistent with the treatment principle for adenomyosis, the treatment principle for CA is to completely remove the lesion, promote fertility and prevent recurrence [6]. Complete resection of the adenomyoma and restoration of the normal shape of the uterus can prevent recurrence [7]. According to the location and scope of the lesion, different surgical methods can be selected. According to whether the uterus is retained, surgical intervention can involve conservative surgery or total hysterectomy [8]. CA is more common in women of childbearing age, so it is important to preserve fertility. This disease is a special type of adenomyosis, and there may be residual ectopic endometrium after surgery. Therefore, it is particularly important to take appropriate measures to prevent recurrence. We report for the first time a rare case of a CA secondary to uterine surgery in a 23-year-old woman. Her clinical manifestations were primarily increased menstrual volume without the typical symptom of dysmenorrhea. The patient was successfully treated by the use of conservative surgery combined with gonadotropin-releasing hormone analog (GnRH-a) and a levonorgestrel-releasing intrauterine system (LNG-IUS) for the first time, and no recurrence was found during the 2-year follow-up.

A 20-year-old young woman with no history of pregnancy underwent hysteroscopic submucosal myoma resection. Myoma recurrence was found on reexamination 6 months after surgery. Her menstrual volume had slightly increased, and she had painful menstruation. Since then, there had been a small amount of irregular vaginal bleeding and occasional abdominal distension.

At 21 years old, her ultrasound showed a 4.3 $\times$ 3.4 $\times$ 2.6 cm heterogeneous echogenic mass on the left wall of the uterine cavity and myometrium, which had been only 2.0 $\times$ 1.8 $\times$ 1.3 cm (Fig. 1A) in size according to ultrasonography two months prior. The tumor was close to the serous layer, and multiple nonechogenic masses were distributed within the cavity. The largest nonechogenic mass was 3.4 $\times$ 1.2 cm, and a few blood signals were observed inside of the mass (Fig. 1B). The patient was preliminarily diagnosed with uterine myoma degeneration. The patient’s hemoglobin was 61 g/L. Considering the rapid growth of the tumor and the anemia caused by the tumor, we performed a hysteroscopy examination. Intraoperatively, a mass of approximately 4.5 $\times$ 3.5 $\times$ 3.0 cm found in the left side wall of the uterine cavity near the angle of the uterus, and its surface was dark red. The base was approximately 3.5 cm wide, the internal protrusion was approximately 70%, the intima was thin, the right fallopian tube opening was visible, and the left fallopian tube opening was unclear. After that, she underwent hysteroscopic surgery. From the free edge of the mass, the mass was cut with a 90-degree circular monopole, and 30 units of oxytocin were used to promote the protrusion of the mass into the uterine cavity. The tumor was found to be soft with an unclear boundary and could be caved in with pressure. The tumor protruding from the uterine cavity was removed. The tumor was approximately 0.5 cm from the serous layer after resection. A small amount of unresectable fibroid tissue with a diameter of approximately 0.5 cm was found under ultrasound guidance. Strict electrocoagulation was used to stem bleeding, and the uterine cavity returned to its normal shape. The postoperative pathology showed adenomyoma of the uterus. One month after the operation, hysteroscopy reexamination showed a normal uterine cavity, with no obvious fibroids in the cavity. The patient was not subsequently reexamined.

Fig. 1.

Ultrasound tomographs of the patient. (A) At the age of 21, the patient’s first ultrasound examination showed a mass with mixed echogenicity in the uterine cavity of 2.0 $\times$ 1.8 $\times$ 1.3 cm in size, with 3–4 echogenicity points and no obvious blood flow signal. (B) At the age of 21, her ultrasonography 2 months later showed a 4.3 $\times$ 3.4 $\times$ 2.6 cm heterogeneous echogenic mass on the left wall of the uterine cavity and myometrium (close to the serous layer), with multiple nonechogenic masses distributed within the cavity. The largest nonechogenic mass was 3.4 $\times$ 1.2 cm, and a few blood signals were observed inside the mass. (C) The ultrasound demonstrated two hypoechoic nodules in the posterior wall of the uterus, 4.3 $\times$ 3.3 cm and 4.1 $\times$ 3.0 cm in size; the two nodules were fused and protruded into the uterine cavity.

At the age of 23, the woman was hospitalized for four months due to increased menstrual flow. Before admission, her menstrual volume had increased over the past 4 months to approximately 1.5 times the original menstrual volume. She had no dysmenorrhea or changes in the menstrual cycle or menstrual period. Ultrasound demonstrated two hypoechoic nodules in the posterior wall of the uterus, 4.3 $\times$ 3.3 cm and 4.1 $\times$ 3.0 cm in size; the two nodules were fused and protruded into the uterine cavity (Fig. 1C). She was initially diagnosed with submucous uterine myoma. Her hemoglobin was 85.00 g/L. The carbohydrate antigen 125 level was 44.14 U/mL. Considering that the patient was young, had a desire to have children in the future and that the tumor was the cause of anemia, we treated her with laparoscopic surgery for adenomyoma excision and a levonorgestrel-releasing intrauterine device (LNG-IUD) was inserted. Her uterus had a smooth surface and had increased in size to that of a 2-month pregnancy. On the left side of the uterus, there was a projection of adenomyomatous material with an irregular, lobulated shape and a diameter of approximately 8 cm that contained cystic spaces of 1–2.5 cm in diameter. The cystic cavity contained a chocolate-colored liquid (Fig. 2). Part of the tumor protruded into the uterine cavity, and part extended into the blood vessels of the muscularis. The 1 : 60 diluted pituitrin was injected into the myometrium around the adenomyoma, and the left lateral myometrium was longitudinally incised by unipolar electrocoagulation under the guidance of ultrasound. The adenomyoma was removed by blunt and retinacular stripping with a diameter of approximately 8 cm, and the endometrium was penetrated to approximately 1 cm during the operation. The myometrium was continuously sutured with absorbable suture line no. 0. After the tissue was put into a specimen bag and cut with an electromechanical morcellator, the fibroid comminuted tissue was removed from the puncture hole in the right lower abdomen by stages. No residual tissue was detected by ultrasound. The LNG-IUD was placed into the uterine cavity. Postoperatively, she was treated with GnRH-a. The postoperative pathology was adenomyoma (Fig. 3). Immunohistochemistry showed SMA (+), Calretinin (-), CD10 part (+), Caldesmon (+), and ki-67 (+) of approximately 2%. She was followed up for 2 years after the operation, and there was no recurrence.

Fig. 2.

(A) On the left side of the uterus, there was a projection of adenomyomatous material with an irregular, lobulated shape and a diameter of approximately 8 cm. (B) When the cyst roof was opened, chocolate-colored fluid flowed out of the lesion.

Fig. 3.

Histologic findings of cystic adenomyosis: hematoxylin and eosin staining: the capsule of cystic adenomyosis is arranged by endometrial glands and the stroma, and around the capsule, the organization has muscular wrapping (A: 50$\mathrm{\times }$ B: 100$\mathrm{\times }$).

CA can be divided into juvenile CA (JCA) and adult CA. JCA is a disease that causes severe dysmenorrhea in women less than 30 years of age with no history of uterine surgery, and imaging findings show cystic lesions with a diameter of $>$1 cm independent of the uterine cavity and covered by the muscular layer [9]. Adult CAs are not well defined and are most common in women over 30 years of age who have a history of previous uterine operations [10].

Injury to the junctional zone (JZ) caused by uterine surgery may be an important factor in the occurrence of adenomyosis [11], resulting in the invasion of the basal endometrium into the myometrium, causing regeneration, healing and changes in the size [12]. We report a rare case of CA in a patient under the age of 30 who had a history of uterine surgery and could not be diagnosed with either JCA or adult CA. She should be considered to have secondary CA associated with surgery. Our patient’s secondary adenomyoma may have been associated with JZ injury during myomectomy, leading to endometrial invasion of the myometrium. This hypothesis is supported by the fact that patients recurred only 6 months after surgery. The second surgery probably resulted in the development of CA. Adenomyoma of the uterus partly protruded from the uterine cavity and partly extended to the muscularis vessels, increasing the possibility of intraoperative JZ injury. Intraoperative ultrasound scans revealed residual tissue from secondary surgery, although intraoperative tight electrocoagulation and postoperative hysteroscopy showed no residuals. The location of the cystic lesion was the same as before, and symptoms of increased menstrual volume appeared. This confirms the possibility of surgical residual tissue or JZ injury.

In the pathology of CA, the cyst wall is composed of endometrial glands and stroma, and the surrounding wall is covered with proliferative fibroid tissue [13]. Most cases of CA are confirmed by postoperative pathology [12]. Our patient was misdiagnosed with uterine fibroids before surgery and diagnosed with CA after surgery. Similar to adenomyosis, CA has nonspecific clinical manifestations, such as dysmenorrhea, chronic pelvic pain, abnormal uterine bleeding, etc. [10]. According to a review, patients under 30 years of age with CA are characterized by drug-refractory dysmenorrhea, whereas those over 30 years of age mainly suffer from chronic pelvic pain or sometimes abnormal uterine bleeding [14]. Dadhwal et al. [15] reported two cases of dysmenorrhea in patients under 30 years of age who had no changes in menstrual volume. Pontrelli et al. [16] reported a 27-year-old patient with CA who had increased menstrual volume with dysmenorrhea. We reported for the first time a case of CA in a patient under 30 years of age, whose main clinical manifestation was increased menstrual volume without dysmenorrhea.

Ultrasound is the most commonly used imaging method in the diagnosis of adenomyosis, and it can distinguish between adenomyomas and myomas. The accuracy of ultrasound depends on operator experience and expertise and the quality of the equipment [17]. The sensitivity of transvaginal or transanal ultrasound is higher than that of transabdominal ultrasound [18]. Koukoura et al. [19] reported a case in which transabdominal ultrasound misdiagnosed a patient with an ovarian cyst, but transanal ultrasound and magnetic resonance imaging (MRI) correctly diagnosed CA. MRI can confirm a diagnosis made by ultrasound [20]. MRI can accurately assess the contents of CA, endometrial and muscular tissue, and the junction area. The fluid in the cysts shows a high signal intensity on T1-weighted images, and the surrounding muscular layer shows low signal intensity on T2-weighted images [10, 21]. Hysteroscopy can diagnose adenomyosis according to the special microscopic manifestations [22]. Hysteroscopy can differentiate JCA from congenital developmental abnormalities, such as biangular uterus or ovarian cysts, and the lesions can be sampled to obtain pathological specimens for a definitive diagnosis [16]. Alabiso et al. proposed a new decision algorithm based on a 28-year-old infertility patient with uterine adenomyosis. First, the diagnosis was made by ultrasound and then confirmed by MRI. Then, hysteroscopy or laparoscopy was performed, and finally, a detailed diagnosis and treatment plan was made [12]. Unfortunately, our patient was misdiagnosed with uterine fibroids by ultrasound, and no further MRI examination was performed, nor was the mass sampled for pathological examination during hysteroscopy. MRI is very important for adenomyosis patients, especially for the identification of recurrent myoma lesions in young patients. Hysteroscopy is also very important for the diagnosis and treatment of intrauterine masses.

Surgery is an important means to treat adenomyosis, drugs can also treat it [23]. Drug treatments include GnRH-a, nonsteroidal anti-inflammatory drugs, LNG-IUS, etc. Drugs can only relieve symptoms, and recurrence can occur after drug withdrawal [24]. There are very few reports about CA drug therapy. Zhou et al. [25] reported a case of adult CA patient with significantly reduced symptoms after LNG-IUS treatment. Intraoperative residual lesions or JZ damage may cause recurrence. Surgery may lead to an adverse pregnancy history [26]. According to previous reports, conservative surgery combined with GnRH-a or an LNG-IUS can prevent recurrence and relieve dysmenorrhea and other symptoms and improve the fertility of patients [27, 28, 29]. There is a lack of reliable reports on pregnancy outcomes of CA.

In our patient, her lesion was completely excised by ultrasonic monitoring, and the mass was put into a sample bag and removed from the puncture hole by stages, further reducing residual tissue in the abdominal cavity. GnRH-a and an LNG-IUS were used for postoperative treatment to reduce symptoms and prevent recurrence. We report for the first time the successful treatment of a secondary CA patient under 30 years of age with surgery and medication. This case also has the longest follow-up to date. She was followed up for nearly 2 years without recurrence or obvious discomfort. Her pregnancy outcomes require further follow-up.

Younger patients with a history of uterine surgery may have secondary CA, and the clinical manifestations may not include the typical unbearable dysmenorrhea. For patients with unclear ultrasound diagnoses, MRI examination is very important.

For patients with intrauterine lesions, hysteroscopy can obtain a sample for pathologic diagnosis or treatment. Complete intraoperative excision of the lesion and reduction in residual tissue, combined with postoperative treatment with GnRH-a and an LNG-IUS, can effectively prevent recurrence and improve prognosis. The prognosis and pregnancy outcomes of CA are still not clear, and further study is needed.

CA, Cystic adenomyosis; GnRH-a, gonadotropin-releasing hormone analog; JCA, juvenile adult cystic adenomyosis; JZ, junctional zone; LNG-IUD, levonorgestrel-releasing intrauterine device; LNG-IUS, levonorgestrel-releasing intrauterine system; MRI, magnetic resonance imaging.

HXL, KJS, NNX and QY participated in the diagnosis and management of this case. XYJ and LS followed up the patient HXL wrote the manuscript. QY revised the manuscript. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institution, and written consent was obtained. The study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics Committee of Affiliated Hospital of Qingdao University (approval number: QYFY WZLL 25965).

Thanks to all the peer reviewers for their opinions and suggestions.

This research received no external funding.

The authors declare no conflict of interest.