Isolated intracranial myeloid sarcoma as an acute myeloid leukemia relapse: A case report

Abstract Introduction/Objective Adequate assessment during intraoperative consultation on a patient with a brain mass is imperative to provide critical information that will direct the therapeutic approach during surgery. Methods/Case Report The patient is a 67-year-old female with acute myeloid leukemia (AML) on maintenance therapy and in remission for the past 2 years that developed altered mental status and seizures. Imaging revealed a diffuse intra-axial mass within the corpus callosum and right hypothalamic region. A brain stereotactic biopsy was performed. Blood work showed mild leukopenia (3.63x109/L), thrombocytopenia (platelet count of 82x109/L), and an essential normal hemoglobin level of 11.9 g/dL. A frozen section assessment during intraoperative consultation revealed an infiltration of small blue cells, suggesting a hematolymphoid process. Further histological assessment showed small to intermediate-sized monomorphic cells in sheets and around the vessels with open fine chromatin, prominent nuclei, and scant cytoplasm admixed with tingible body macrophages. Differential diagnoses included high- grade B-cell lymphoma, Burkitt lymphoma, mantle cell lymphoma blastoid variant, lymphoblastic lymphoma, and myeloid sarcoma (MS). The tumor cells were positive for CD34, CD43, and MPO (subset) and negative for CD20, PAX5, TdT, CD3, and AE1/AE3 by immunohistochemical staining, consistent with MS. Concurrent bone marrow biopsy with flow cytometric evaluation showed progressive trilineage hematopoiesis without evidence of residual leukemia. Results (if a Case Study enter NA) NA Conclusion Intracranial MS is extremely rare, and literature reviews are limited to primarily case reports. MS can occur before, during, or after the initial presentation of AML. Interestingly, this patient had an isolated intracranial myeloid sarcoma as an AML relapse without bone marrow involvement. We aim to increase the awareness of isolated recurrence of AML in the form of an intracranial MS; this disease warrants consideration in patients with a history of a myeloid neoplasm who present with neurological symptoms despite the absence of peripheral disease.