BCR/ABL1-positive histiocytic sarcoma of the small intestine in a patient with chronic myeloid leukaemia.

Histiocytic sarcoma (HS) is a rare myeloid-derived neoplasm with histiocytic differentiation and an aggressive clinical course. Recent studies suggest a common clonal origin between various haematolymphoid disorders. However, HS coexisting with chronic myeloid leukaemia (CML) without tyrosine kinase inhibitors (TKIs) has not been reported.