Co-occurrence of Erdheim-Chester Disease and Acute Myeloid Leukemia

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell histiocytosis characterized by recurrent activating mutations in the MAPK pathway. Previous studies have reported that 10.1% of patients with ECD develop concomitant myeloid neoplasms, such as chronic myelomonocytic leukemia (CMML), acute myeloid leukemia (AML), myelodysplastic syndromes (MDS)/myeloproliferative neoplasms (MPN), essential thrombocytosis (ET), myelofibrosis (MF) and polycythemia vera (PV). Here we describe a unique case of simultaneous ECD and AML at initial diagnosis, followed by clonal evolution of AML subclones with FLT3-ITD and PTPN11 mutation in an elderly male patient.