Medical Laboratory Scientist (MLS) ASCP Exam 2025 – 400 Free Practice Questions to Pass the Exam

Acute Monoblastic Leukemia is classified under the French-American-British (FAB) classification system as FAB M5. This type of leukemia primarily involves the proliferation of monoblasts, which are precursor cells to monocytes. In FAB M5, the blast cells characteristically have a high degree of variation in their morphology and often include a significant population of monoblasts along with promonocytes.

The essence of FAB M5 is its focus on the monocytic lineage, which distinguishes it from other subtypes in the FAB classification, such as M1 (acute myeloblastic leukemia without maturation), M3 (acute promyelocytic leukemia), and M4 (acute myelomonocytic leukemia) that include different types of blast cells. Each of these categories describes specific characteristics and lineages of the leukemic cells, which are essential for accurate diagnosis and treatment planning. Thus, understanding the classification helps medical laboratory scientists in identifying the leukemic cells and providing appropriate patient care.