AML-005: Primary Central Nervous System Myeloid Sarcoma Evolving from a Myeloid Neoplasm with Eosinophilia Associated with FIP1L1-PDGFRA

Background Myeloid sarcoma (MS) is an extramedullary tumor of immature myeloid cell origin usually concurrently or in the evolution of acute leukemias or with known chronic myeloproliferative disorders. It has been rarely identified isolated without medullary involvement. Most common sites of involvement are skin, lymph nodes, soft tissues and bone. Isolated central nervous system (CNS) primary MS are extremely rare. They may involve the subperiosteum and dura mater and, on rare occasions, can also invade the brain parenchyma. Aims To describe a case of an isolated CNS myeloid sarcoma. Methods Case. A 42-year-old man with a history of chronic eosinophilia with FIP1L1-PDGFRa rearrangement was admitted with headache, aphasia and confusional syndrome. MRI showed a 49 × 47 mm heterogeneous left temporal tumor. Laboratory findings were as follow: hematocrit 46%, WBC 13×103/l (neutrophils 66% eosinophils 12%), platelet count 150×103/ul. Renal and hepatic function tests were normal. Hepatitis and HIV serology were negative. A positron emission tomography scan showed no abnormal uptake. Brain tumor exeresis was done. Pathology findings were compatible with myeloid blastic infiltration. Immunohistochemical analysis was positive for CD45 (leukocyte common antigen) and myeloperoxidase. Bone marrow biopsy showed no infiltration. Cytogenetics was 46, XY, +7, +8, +10. Molecular analyses of FLT3, inv16, t(8;21), BCR-ABL1 and JAK2V16F were negative. Results Based on the diagnosis of myeloid sarcoma evolving from a myeloid neoplasm with eosinophilia associated with FIP1L1-PDGFRA, he was treated with 3+7 (cytarabine + daunorubicine) plus imatinib induction chemotherapy. Then, he received 1 consolidation cycle of high-dose cytarabine plus mitoxantrone and allogeneic bone marrow transplant. Summary/Conclusion Myeloid sarcoma diagnosis is challenging. De novo MS is rare and unfortunately there is no treatment guidelines. AML-based therapies are recommended.