Cancer-related microangiopathic hemolytic anemia (CR-MAHA) in a metastatic breast cancer patient with a germ-line ATM single nucleotide variant and an ESR1 fusion variant: insights from a case report on early diagnosis and improved outcomes

Cancer-related microangiopathic hemolytic anemia (CR-MAHA) is a rare and life-threatening paraneoplastic syndrome that carries a poor prognosis if not recognized early. While existing reports primarily focus on clinical outcomes, the underlying molecular changes remain poorly understood. We present a case in which the patient initially presented with back pain and fatigue. Further diagnostic workup confirmed the diagnosis of CR-MAHA, and she was promptly initiated on treatment, resulting in an excellent clinical anti-tumor response and resolution of the hemolytic anemia. Genomic testing revealed a germ-line ATM single nucleotide variant and an ESR1 fusion variant. This case raises important questions regarding potential genomic alterations that may predispose individuals to CR-MAHA and underscores the necessity for further investigation of tumor samples from these patients using both DNA and RNA sequencing.