Clinicopathological characteristics of de novo and secondary myeloid sarcoma: A monocentric retrospective study

ObjectiveDiagnosing myeloid sarcoma remains challenging, and we aimed to provide clinicopathological features to facilitate diagnosis. MethodClinicopathological data from 41 patients with de novo and 31 with secondary myeloid sarcoma were reviewed. ResultsMost de novo cases presented with isolated myeloid sarcoma (n=19) or myeloid sarcoma with concurrent acute myeloid leukemia (n=15). Most secondary cases presented after acute myeloid leukemia (n=11), myeloproliferative neoplasm (n=9), or myelodysplastic syndrome (n=8). Most frequent localizations were skin and lymph nodes. Immunohistochemistry showed immature and/or aberrant antigenic expression in 29% of de novo and 39% of secondary cases. Most genetic abnormalities were RUNX1-RUNX1T1 (n=4), CBFB-MYH11 (n=2), KMT2A-MLLT3 (n=2), and JAK2 V617F (n=2) mutations in de novo myeloid sarcoma, and BCR-ABL1 (n=5) and KMT2A rearrangements (n=2) in secondary cases. A complex karyotype was seen in 17% of de novo and 39% of secondary cases. Most prevalent treatment was induction chemotherapy followed by consolidation chemotherapy (n=10) or allogeneic stem cell transplantation (n=9) for de novo and radiotherapy (n=11) for secondary cases. ConclusionDe novo myeloid sarcoma mostly presented isolated. Lesions were often localized at skin and lymph nodes. Genetic aberrations frequently involved core-binding factor rearrangements in de novo cases and a complex karyotype in secondary cases.