Primary myeloid sarcoma in an infant with an NRAS mutation

Abstract

To the Editor, Myeloid sarcoma (MS), a rare extramedullary tumor of immature myeloid cells, was first described in 1811 by Allen Burns and was added to the updated acute myeloid leukemia (AML) classification system by World Health Organization in 2016. 1,2,3 MS presents concurrently with or precedes AML in 4−5% of pediatric AML cases and has an association with chronic myeloid leukemia (CML) and myelodysplastic syndrome (MDS). 1,4 Only 14 cases of primary MS without an associated leukemia have been reported in the pediatric population. The most common sites for all MS include the skin, lymph nodes, and bones, with