تسجيل الدخول

تسجيل

Extramedullary Acute Myeloid Leukemia

المؤلف:  Hoffman, R., Benz, E. J., Silberstein, L. E., Heslop, H., Weitz, J., & Salama, M. E.

المصدر:  Hematology : Basic Principles and Practice

الجزء والصفحة:  8th E , P947-948

2026-10-13

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 Typically, AML is characterized by involvement of the bone mar row and peripheral blood, but it may also infiltrate into other tissues, termed extramedullary AML. This may be concurrent with marrow or blood involvement or may be isolated, such as in the case of myeloid sarcoma or chloroma. The pathobiology that results in extramedullary manifestations of AML remains poorly understood. Common sites of extramedullary disease include in the skin, termed leukemia cutis, as well as in soft tissues or the central nervous system (CNS). Certain clinicomorphologic features are associated with extramedullary AML, including monocytic differentiation (notable for mucosal infiltration) and hyperleukocytosis.

Comprehensive or reliable molecular and cytogenetic characterization of extramedullary AML is limited in scope and generally retrospective in nature; however, prior reports suggest an increased frequency of extramedullary disease in CBF-AML—particularly t(8;21)—as well as APL. Other cytogenetic and molecular alterations that appear to be enriched in myeloid sarcoma include trisomy 8, and mutations in NPM1 or FLT3-ITD. There may also be interactions with immune surveillance that lend to extramedullary disease involvement, particularly in disease relapse, including following allogeneic hematopoietic cell transplantation. Some studies have identified T-cell exhaustion as a possible mechanism of extramedullary relapse, with upregulated immune checkpoint expression on biopsy of leukemic infiltrates.