Low deviation adenocarcinoma of the uterine cervix is a rare clinical cervical cancer with lack of specificity in symptoms and signs and mild pathological histological changes, which makes it easy to be missed and misdiagnosed. In this paper, we discuss the clinical characteristics of cervical MDA and the causes of misdiagnosis by synthesizing the domestic and international literature, in order to help clinical diagnosis. Case sharing: The patient, female, 54 years old. She was admitted to the hospital with abdominal pain and distension for more than 1 month after 8 years of menopause. Physical examination: stable vital signs, no cardiopulmonary abnormalities, slightly distended abdomen, suspicious mobile turbid sounds (+), no special remaining. Gynecological examination: cervical hypertrophy in the shape of a barrel, about 5 cm in diameter, surface like cauliflower-like hyperplasia, hard, with contact bleeding, loss of vaginal vault structure; uterus anteriorly positioned, slightly large, a 5.0 cm × 4.0 cm × 2.0 cm size irregular mass can be palpated behind the uterus, indistinctly demarcated from the uterus, light pressure pain, fixed; bilateral thickening of the adnexal area can be palpated; tricuspidation can be palpated bilateral uterosacral, main ligament The main ligament was thickened, shortened and inelastic. Gynecologic ultrasound examination showed that the uterus was enlarged, and a 5.3 cm×5.1 cm mixed mass was seen between the posterior cervical area and the uterine body, which was closely related to the uterus, and the blood flow signal was not abundant. CT scan of the pelvis showed that the cervical area was about 3.5 cm×3.0 cm in size, the cervical canal was slightly dilated, the edges were slightly hairy, and the density of the muscular layer was not uniform; no obvious abnormal density shadow was seen in the rectal fossa of the uterus; multiple nodular and striated hyperdensity shadows were seen next to the pelvic wall bilaterally, cervical changes were considered, cervical cancer was not excluded, and interstitial myoma and degeneration of the posterior wall of the uterus were possible. Thin layer liquid-based cytology (TCT) showed: a small number of abnormal DNA ploidy cells (1 to 2); human papillomavirus (HPV) test (-). Cervical biopsy showed atypical hyperplasia of the glandular epithelium in clusters and papillary hyperplasia of some of the glandular epithelium; later, another cervical biopsy under colposcopy showed atypical hyperplasia of the cervical glandular epithelium. The clinical diagnosis was cervical cancer. A dissection was performed under general anesthesia. Intraoperatively, we saw: yellow peritoneal fluid of about 800 ml, pelvic and abdominal peritoneal surfaces were covered with corn-like hard nodules, liver was not involved, no metastatic nodules under the diaphragm, stomach and small omentum were not involved, multiple nodules of soy size at the spleen tip, large omentum was involved with hard texture in the shape of “pie”, mesenteric and intestinal canal surfaces were covered with nodules of rice grain to soy size; The uterus was slightly larger, the left ovary was about 4.0 cm × 4.0 cm × 3.0 cm in size, the right ovary was about 4.0 cm × 3.0 cm × 2.0 cm in size, and a few nodular tissues were seen on the surface of both ovaries; there was an irregular hard mass between the uterus, bilateral adnexa and rectum, close to the pelvic wall on both sides, involving the posterior wall of the uterus and the anterior wall of the rectum anteriorly and anteriorly, respectively; there was a nodule about 3.0 cm × 3.0 cm × 2.0 cm at the junction of the sigmoid colon and the rectum. A nodule about 3.0 cm×3.0 cm×2.0 cm in size at the junction of the sigmoid colon and rectum, the base and posterior wall of the bladder were involved, and the cervix formed dense adhesions with the surrounding tissues. Intraoperative resection of bilateral adnexa, large omental nodules and abdominal implantation nodules were sent for frozen pathological examination, suggesting that mucous glandular infiltrative growth was seen in the fibrous tissue, and the glandular epithelium was mostly monolayer, mildly heterogeneous, and nuclear schizophrenia was seen, with possible malignant tumor. Considering widespread tumor metastasis, total hysterectomy + bilateral adnexal resection + large omentectomy + abdominal implantation node resection was performed after communication with the family, because the uterine tissue was brittle and decayed, the posterior uterine mass could not be completely removed. Postoperative pathology report: cervical MDA, involving the whole cervix, uterine body and parametrium, ovarian, fallopian tube, greater omentum and abdominal metastases were highly differentiated mucinous adenocarcinoma; immunohistochemistry (histochemistry) showed: CEA, CK7 were (+), CK20, ER, PR were (-), Ki-67 about 5%, P53 about 3% (+). Postoperative diagnosis: cervical MDA (stage IVB), now under simultaneous radiotherapy. Discussion 1. Clinical features MDA of the uterine cervix is a highly differentiated malignant adenocarcinoma, accounting for only 1% to 3% of cervical adenocarcinomas, which was classified as a subtype of mucinous adenocarcinoma by the new World Health Organization (WHO) classification in 2003. The age of onset of MDA ranges from 25 to 76 years, with an average of 45 years. The main symptoms include vaginal discharge of large amounts of thin mucus, irregular vaginal bleeding, intermittent lower abdominal pain and contact bleeding. Gynecological examination reveals a marked hypertrophy of the cervix, with a barrel-shaped thickening or fist-shaped, hard and fixed texture, some of which may be accompanied by cervical redundancy, while some patients may have a completely normal cervical shape. Most scholars believe that the typical clinical manifestations of cervical MDA are massive vaginal discharge and cervical dilatation. It has been reported in the literature that about 11% of patients with cervical MDA have a combination of melanotic polyposis (Peutz-Jeghers syndrome). 2. Diagnosis and differential diagnosis Cervical cytology has limited diagnostic value for MDA, and high-risk HPV testing is often negative in such patients. In this case, the cervical cytology examination showed slight abnormal changes and the HPV test was negative. The typical pathological features of MDA are as follows: (1) highly differentiated mucinous adenocarcinoma, most of the glands are indistinguishable from normal glands; (2) most of the glands are covered with pseudostratified columnar epithelial cells, which are mucus-rich and have basal nodes; a few glands have moderate nuclear atypia or pro-fibrous connective tissue hyperplasia; (3) most of the glands are covered with pseudostratified columnar epithelial cells, which are mucus-rich and have basal nodes. Interstitial reaction; (3) most glands have a disorganized arrangement with active mitotic activity; (4) infiltration of blood vessels or nerve bundles; (5) the depth of glandular infiltration is a very important histopathological feature of the disease. Immunohistochemistry showed positive or strong positive expression of CEA, P53, and Ki-67, among which the positive expression of CEA was more stable; while HPV16, HPV18, PR and CA125 were mostly not expressed. In addition, special staining of AB/PS mucus showed red reaction, indicating abundant neutral mucus in the lumen of the gland. The main differentiation points are as follows: MDA patients mostly present with a large amount of thin mucus-like vaginal discharge and abnormal hypertrophy of the cervix; pathologically, the main observation is whether there is infiltration and the degree of glandular distribution, characterized by diffuse uniform distribution of scattered glands, infiltrative growth, but the glandular structure is heterogeneous. The nucleus has different degrees of heterogeneity, most of them are mildly heterogeneous and mainly monolayered, and its cytoplasm is richer than that of highly differentiated cervical adenocarcinoma and cervical glandular atypical hyperplasia. The early diagnosis of clinical cervical MDA is difficult, and the literature reports that the rate of missed diagnosis and misdiagnosis is as high as 34%. Cervical biopsy is the basis for a clear diagnosis, but the study reported that the first cervical biopsy confirmed the diagnosis rate of only 31.25% to 38.50%. This is due to the fact that MDA is highly differentiated histologically, the tumor cell heterogeneity is not obvious, and the clinical and pathological features of benign cervical lesions are extremely similar to those of MDA, making it difficult to diagnose and the early diagnosis rate is low. Many patients often have difficulty in obtaining a diagnosis even after multiple cervical biopsies. In this case, two preoperative cervical biopsies and intraoperative rapid frozen pathology sections failed to make a clear diagnosis. He Mian et al. reported a case of cervical MDA that was misdiagnosed as chronic cervicitis after 5 cervical biopsies within 51 months. Zhang Yang et al. reported a case of cervical MDA in which three cervical and vaginal biopsies were performed in different hospitals without a clear diagnosis, and the patient had lost the opportunity for surgical treatment when the diagnosis was confirmed. This case was already in advanced stage of cervical cancer, but it was still misdiagnosed. Combining with the domestic and foreign literature, the following factors may be related to the misdiagnosis: (1) the clinicians did not have a comprehensive understanding of the disease and believed too much in medical examination, and one-sidedly thought that the patient did not have a large amount of vaginal discharge, and considered the possibility of myxoma and degeneration in the posterior wall of the uterus according to pelvic CT scan. (2) The cervical biopsy specimen was taken less or the site was too superficial, and the depth and width of the tissue was small so that the infiltrated part of the cervix or the part with obvious lesions might be overlooked. (3) Inadequate understanding of pathological diagnosis of MDA by pathologists. Pathologists have insufficient understanding of the diagnostic criteria of MDA and its differential diagnosis with cervical adenocarcinoma and benign cervical glandular proliferative lesions; secondly, different pathologists have different understanding of microscopic cellular atypical proliferation and infiltration, resulting in misdiagnosis or omission. 4. Countermeasures to prevent misdiagnosis Both clinical and pathologists should raise awareness of rare and uncommon diseases, and when receiving patients with high suspicion of cervical MDA, deep biopsy (>5 mm) should be performed on their cervix to facilitate the search for evidence of deep infiltration, and cervical conization should be performed as early as possible if necessary. The clinical department should strengthen the communication with the pathology department and provide the pathologist with informative and rich clinical data. The pathologist should take a wide range of materials and perform serial sections, and add immunohistochemical staining and special staining to assist in the diagnosis, so as to strive for early diagnosis and treatment and avoid missed diagnosis and misdiagnosis, thus preventing patients from missing the best treatment period.