A case of concurrent Erdheim–Chester disease and acute myeloid leukaemia diagnoses with postulated shared clonal ancestry

Erdheim–Chester disease (ECD) is a rare, histiocytic neoplasm of myeloid origin, characterised by somatic MAPK signalling pathway mutations. The resulting histiocytic proliferation and subsequent multisystemic accumulation causes hallmark clinicopathological and radiological features of the disease. Myeloid neoplasms, either concurrent or subsequent, have been reported in a subset of ECD cases. The development of both ECD and overt myeloid malignancies from underlying clonal haematopoiesis with sequential acquisition of driver mutations has been proposed.