(Disclaimer: This article is for scientific purposes only, in order to protect the patient’s privacy, the relevant information in the following content has been processed) Abstract: Appendiceal mucinous adenocarcinoma is a disease with a high recurrence rate, and rupture of the cyst can easily lead to abdominal dissemination, so eradication of the lesion and prevention of recurrence are very important. The patient in this article is a 72-year-old man who was admitted to the hospital with increasing abdominal pain. After the interview, the diagnosis of appendiceal mucinous adenocarcinoma was confirmed by combining the family history, imaging, and pathological examination, and the patient continued to recover through surgery + chemotherapy, and no tumor metastasis has been detected during the follow-up period. Basic information] Male, 72 years old [Disease type] Appendiceal mucinous adenocarcinoma [Hospital] The First Affiliated Hospital of Kunming Medical University [Date of consultation] June 2021 [Treatment plan] Surgery (appendectomy) + chemotherapy (oxaliplatin + capecitabine) [Period of treatment] Inpatient treatment for 2 weeks, follow-up for 3 months [Effect of treatment] Patient gradually recovered from the surgery, and tumor metastasis has not yet been found during the follow-up period. I. Initial Consultation On a morning in June 2021, an elderly male patient was admitted to our department through the emergency department. The patient was lying on the bed, half-curled up, with both hands pressed on his right lower abdomen, with a painful expression and a lot of sweat. The patient said that his stomach had been hurting for a while, starting from breakfast, at first there was just a little pain, but later he felt that the pain was getting worse and worse, and now the pain was more severe. After understanding, the patient said that he was constipated a few days ago, and his lower stomach was bloated and sometimes a little painful, which caused him to have little appetite for eating, and he wanted to vomit a little bit after eating, but he could be well after a while. On physical examination, a mass was found in the right lower abdomen, which was suspected to be appendicitis. However, I asked the patient if his family had any history of tumor, and the patient told me that his brother died of cancer last year, so I suggested him to be hospitalized for detailed examination to rule out malignant tumor of the appendix. After the patient was admitted to the hospital, physical examination revealed an obvious mass in the right lower abdomen, and ultrasound showed that there was a small amount of ascites in the abdominal cavity. Next, the patient underwent CT and MRI, which showed that the thickening of the appendiceal wall was about 16 millimeters, and it was decided to perform a surgical operation on the patient, during which the tumor was seen to have infiltrated through the wall of appendix, and the tumor had infiltrated through the whole appendiceal layer locally but no obvious metastasis had been detected in other parts. Therefore, radical appendectomy was performed, and the tissue was sent to pathology for examination after surgery, and it was determined to be appendiceal mucinous cystadenoma. In order to avoid abdominal dissemination of the tumor, oxaliplatin combined with capecitabine was added for adjuvant chemotherapy after surgery. When the patient was admitted to the hospital, the tumor had infiltrated the whole layer of the appendix, but because the growth of the tumor was relatively limited, no obvious metastatic foci had been found yet, so the surgical resection process was relatively clear and the operation was relatively successful. However, due to the patient’s age and weak physical condition, the patient’s recovery after appendectomy was slower than that of other patients with stronger physical condition, but the patient’s condition turned out to be better and he was discharged from the hospital after 2 weeks of hospitalization. During the 3-month postoperative follow-up period, no tumor metastasis was detected by CT, MRI and other imaging tests, and the patient needs further long-term observation. IV. Precautions Truly happy for the patient’s gradual recovery and improvement. As appendiceal mucinous cystadenoma is prone to abdominal dissemination, the patient should be re-examined every month after discharge, and if any discomfort occurs during the follow-up period, the patient should consult the doctor immediately, so as to avoid delaying the diagnosis and treatment of the disease. As the patient has mucus ascites in the early stage, the probability of recurrence is high, the patient should always be vigilant, follow the doctor’s instructions to receive chemotherapy, do not change the number of times and dosage of medication without authorization. In life, it is recommended that patients should go down to the ground more often, choose some easily digestible and highly nutritious food in diet, and keep optimistic mood. V. Personal insights The common symptoms of appendiceal mucinous carcinoma are abdominal pain, abdominal distension, nausea, constipation, etc., which are very similar to the symptoms of appendicitis and enteritis, and thus will not attract the attention of patients, and will easily lead to the misdiagnosis by doctors, so that both patients and doctors should be more vigilant. In addition, appendiceal mucinous adenocarcinoma is a kind of disease with high recurrence rate, and the rupture of the cyst can easily lead to abdominal dissemination. Therefore, the recovery process is a long-lasting battle for the patients, and their family members should frequently monitor the patients’ diets, digestive and defecation conditions, and give more encouragement to the patients to build up confidence for the patients.