Myeloid Sarcoma : Microscopic
Myeloid sarcomas show a spectrum of histologic features. The tumors can be subclassified according to the most abundant cell type into granulocytic, monoblastic, myelomonocytic or megakaryocytic and according to the degree of differentiation into blastic, immature, and differentiated types. Blastic type of myeloid sarcoma is composed predominantly of myeloblasts with little or no evidence of maturation. The immature type is intermediate grade and consists of myeloblasts, promyelocytes, and eosinophilic myelocytes. The mature type is better differentiated and shows mature granulocytes with an abundance of eosinophils. This photomicrograph is from a myeloid sarcoma of femur in a 65 y/o male who presented with a pathological fracture. The tumor is composed of diffuse sheet of myeloblasts, promyelocytes, and eosinophilic myelocytes (better visualized in the next image.