Myeloid Sarcoma Involving the Central Nervous System Without Evidence of Preexisting Hematologic Disease: A Case Report

Abstract

Abstract Introduction/Objective Myeloid sarcoma within the central nervous system is a rare presentation of an infiltrative mass of immature myeloid cells. It is typically found in association with myeloid dysplastic syndrome, myeloproliferative disorder, or acute myeloid leukemia. Rarely, it can occur in the absence of these diseases. Methods We present the case of 68-year-old female with worsening nausea and headaches. Brain MRI showed diffuse pachymeningeal enhancement with numerous nodular enhancing extra-axial masses overlying both cerebral hemispheres. Results Open biopsy of these masses showed gelatinous, hemorrhagic, brown tissue measuring 3.0 x 2.0 x 0.7 cm. Histologically, the specimen shows a diffuse polymorphous atypical myeloid proliferation consisting of all three cell lineages. There are nodules composed predominantly of large blastoid cells with 1 to 2 prominent oblong nucleoli, consistent with erythroblasts and early erythroid precursors. In between the nodules there are myeloid cells in different stages of maturation, including numerous eosinophilic precursors. Scattered megakaryocytes are also identified. Immunohistochemistry shows positivity for E-cadherin, CD235a and spectrin which highlight the immature erythroid cells. MPO, muramidase, and CD33 are positive in myeloid elements. Eosinophilic peroxidase highlights numerous eosinophilic precursors. CD34 is positive in the endothelial cells and very rare hematopoietic cells. CD20 and PAX 5 highlights B-cells, CD3 highlights T-cells, and CD4 highlights monocytic precursors, monocytes, histiocytes and a subset of T-cells. Conclusion Additional work up at the time of biopsy including FLOW cytometry and bone marrow biopsies showed no evidence of hematologic pathology. In summary the histologic and immunohistochemical findings demonstrate a tumor composed of proliferating immature myeloid cells most consistent with myeloid sarcoma without any evidence of hematological disease.