RESUMEN
In about half of the cases, autoimmune hemolytic anemia (AIHA) is secondary to an underlying disease, often due to paraneoplastic syndromes. Recently, the number of patients developing metachronous multiple primary malignant tumors (MPMTs) has been increasing due to the aging of the population and the longer survival times of those with malignant tumors. A 78-year-old woman was diagnosed with sigmoid colon cancer in May 2017 and with warm AIHA in October 2017. She received prednisolone for her warm AIHA treatment, which relieved her anemia symptoms. In January 2020, she had a warm AIHA relapse and received PSL again. In May 2020, she was diagnosed with peritonitis due to a small intestinal perforation and underwent laparoscopic partial resection of the small intestine. Subsequently, she was diagnosed with diffuse large B-cell lymphoma. It is important to consider the possibility of MPMTs and perform the appropriate examinations to determine whether malignant tumors are present in patients with a history of malignant tumors and a long history of AIHA relapse.