Central nervous system involvement by myeloid sarcoma: a report of 12 cases and review of the literature.

Myeloid sarcoma (MS) is an extramedullary malignancy of myeloid origin. It can occur in any organ. Common sites are skin, bone, lymph nodes, and soft tissue. Central nervous system (CNS) involvement is very uncommon. We report 12 new pathology-confirmed cases of CNS MS with literature review. Median age was 42.5 years (range: 0 - 84 years). Bone marrow involvement by hematologic neoplasia was co-incidental (n = 8) or occurred 8 - 51 months prior to CNS MS (n = 3). Abnormal radiological findings detected in all patients, included hemorrhagic (n = 5) or enhancing (n = 2) lesions, with multiple ring-enhancing dura-based masses in 1 patient. Seven tumors had abnormal cytogenetics including: t(11; 19) (q23; p13.3), +8, inv (16), t(9; 22), t(8; 21), del(5q), and +21. One had a complex karyotype and 2 were cytogenetically normal. One MS had the JAK2V617F mutation. Treatment modalities included surgery for decompression (n = 2), radiotherapy (n = 2), chemotherapy (n = 6), and stem cell transplant (n = 2). Nine patients died days to 12 months post CNS MS diagnosis (median = 4 months). Two patients were alive without evidence of disease at 16 and 50 months following MS diagnosis and one was lost to follow-up. The clinical and imaging features for CMS MS overlap with those of intracranial hemorrhage and primary CNS tumors. It is therefore important to maintain a high index of suspicion and perform a biopsy whenever clinically appropriate. A meticulous workup is necessary to avoid misdiagnosis of other hematopoietic or nonhematopoietic neoplasms. Since CNS MS is potentially curable, timely recognition is paramount.