患者，男，63岁，因“间断性黑便1月余，加重7 h”于2019年9月4日至陕西省咸阳市中心医院就诊，以“消化道出血”收治入院。入院时有鲜血便，量多，伴腹痛、腹胀、头晕、乏力、纳差，无其他明显特殊不适。入院后行电子胃镜检查，考虑慢性非萎缩性胃炎伴糜烂；电子结肠镜检查考虑回盲瓣炎；胶囊内镜检查考虑溃疡及肿瘤可能；单气囊小肠镜检查及组织活检证实为单形性嗜上皮性肠T细胞淋巴瘤（monomorphic epitheliotropic intestinal T-cell lymphoma，MEITL）。2019年11月8日患者转院至陕西中医药大学附属医院肿瘤内科；采用R-CHOP方案（利妥昔单抗联合环磷酰胺、阿霉素、长春新碱、泼尼松）化学治疗（化疗）2个周期后，疾病出现进展；化疗方案更换为DA-EPOCH方案（依托泊苷、泼尼松、长春新碱、环磷酰胺和阿霉素）。规范化治疗4个月后，患者病情再次加重，放弃治疗后出院，于2020年3月20日死亡。MEITL因其侵袭性强、恶化程度高、肿瘤负荷重、难确诊及易误诊的特点，患者往往预后不佳，死亡率极高。该文对该例MEITL患者的临床资料进行报道，旨在为后续同类症状患者的诊断和治疗提供参考。

A male patient, 63-year-old, went to Xianyang Central Hospital in Shaanxi Province on September 4, 2019, for "intermittent black stool for more than 1 month with aggravation for 7 h", and was admitted as "gastrointestinal bleeding". On admission, there was fresh blood stool with a large amount, accompanied by abdominal pain, abdominal distension, dizziness, fatigue, and anorexia, without other obvious special discomfort. The electrogastroscopy indicated chronic non-atrophic gastritis with erosion; the electron colonoscopy indicated ileocecal valve inflammation; the capsule endoscopy indicated ulcer and tumor possibility. The patient was finally diagnosed as having monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) after single balloon small bowel microscopy and pathological biopsy. On November 8, 2019, the patient was transferred to the Department of Oncology, Affiliated Hospital of Shaanxi University of Chinese Medicine. After 2 cycles of chemotherapy with R-CHOP regimen (rituximab combined with cyclophosphamide, adriamycin, vincristine and prednisone), the disease progressed and then the therapy was replaced with DA-EPOCH regimen (etoposide, prednisone, vincristine, cyclophosphamide and doxorubicin). After 4 months of standardized treatment, the patient′s condition worsened again; he left hospital after giving up treatment, and died on March 20, 2020. MEITL has the characteristics of strong invasiveness, high degree of deterioration, heavy tumor load, difficult diagnosis and easy misdiagnosis, so the patients often have poor prognosis and high mortality. This article reports the clinical data of this patient with MEITL, aiming to provide reference for the diagnosis and treatment of patients with similar symptoms.