本案例報告為一位75歲男性患有慢性淋巴性白血病，因持續噁心及嘔吐症狀住院，初診斷為消化道出血合併貧血。經胃鏡檢查發現濔漫性胃潰瘍及胃體部腫瘤，胃鏡組織切片病理報告為惡性B細胞淋巴瘤，安排腹部斷層掃描發現肝臟及腹腔內多處淋巴結腫大，行第二次胃鏡切片最後確立診斷為濔漫性巨大B細胞淋巴瘤。由慢性淋巴性白血病發展為高惡性度淋巴癌，此病程進展稱為Richter's症候群。其疾病進展快速具有中高程度的風險，故積極予重新疾病分期，安排骨髓檢查、正子攝影、右腋窩淋巴切片檢查，從症狀開始至確立診斷約一個多月，病患在接受FCR化學治療後，症狀即獲得緩解，病情穩定出院。當病人出現噁心及嘔吐的症狀，經抗潰瘍藥物治療未改善，需行消化道內視鏡檢查，若發現貧血合併體重下降或盜汗等臨床症狀，需高度懷疑癌症之可能性，藉由詳細的病史及身體評估，追蹤檢驗及影像檢查或必要的切片病理輔助，進行相關的鑑別診斷，方能早期確立診斷，以免錯失最佳治療時機。

This case report presents a 75-year-old male with chronic lymphocytic leukemia. He was hospitalized owing to persistent nausea and vomiting. The initial diagnosis was gastrointestinal bleeding complicated by anemia. Gastroscopy showed diffuse gastric ulcers and tumors in the gastric body, and the pathology report of the gastroscopic biopsy suggested malignant B-cell lymphoma. An abdominal CT scan was arranged, which showed multiple enlarged lymph nodes in the liver and abdominal cavity. A second gastroscopic biopsy confirmed the diagnosis of diffuse large B-cell lymphoma. The progression from chronic lymphocytic leukemia to highly malignant lymphoma is known as Richter’s syndrome. The rapid progression of the disease has a medium to high risk of survival. Therefore, we re-staged the disease, and arranged bone marrow examination, positron emission tomography, and right axillary lymph node biopsy. Approximately 1 month after the appearance of symptoms, the diagnosis was established. The patient’s symptoms were relieved after chemotherapy regimon of FCR, his condition was stable, and he was discharged from hospital. When patients present with symptoms of nausea and vomiting that do not improve after anti-ulcer drug therapy, they need to be examined by gastrointestinal endoscopy. If clinical symptoms, such as anemia accompanied by weight loss or night sweats, are reported, the possibility of cancer should be highly suspected. By taking a detailed medical history, physical examination, follow-up examinations, image examinations, or auxiliary pathological examination of biopsies as necessary, differential diagnosis can be made to confirm the diagnosis at the early stage to ensure the best timing for treatment.