Myeloid Sarcoma : Microscopic
Histologic Features of Myeloid Sarcoma (continued): The undifferentiated (or blastic) tumors can resemble diffuse large B-cell lymphomas. The myeloblasts are arranged in diffuse sheets or single (Indian) file pattern between fibrous septa and efface the underlying tissue architecture. They have round or folded vesicular nuclei with finely stippled nuclear chromatin.
In more differentiated cases, the myeloblasts are admixed with maturing granulocytes, erythroid precursors, and megakaryocytes (as seen here). The cells easiest to recognize are eosinophilic myelocytes with their distinctive orange cytoplasm (as nicely seen in this case). However, they are present only in a small percentage of cases.