Which feature differentiates ALL L2 from ALL L1?

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Multiple Choice

Which feature differentiates ALL L2 from ALL L1?

In the FAB classification of acute lymphoblastic leukemia, the difference between the L1 and L2 subtypes rests on how the lymphoblasts look under the microscope. L1 features are small, uniform lymphoblasts with scant cytoplasm and smooth, consistent nuclei. L2, on the other hand, has larger, more variable lymphoblasts with irregular nuclear contours and clefts or indentations in the nuclei. That nuclear clefting is the telltale sign that separates L2 from L1. So, the distinguishing feature is nuclear clefting on the lymphoblasts. The idea is that L1 blasts are uniform and lack clefts, while L2 blasts show clear nuclear irregularities, including clefts. Auer rods point to myeloid lineage rather than lymphoid, so they wouldn’t differentiate L1 from L2. Erythroid precursor abundance isn’t a defining feature for these two lymphoblastic subtypes.

In the FAB classification of acute lymphoblastic leukemia, the difference between the L1 and L2 subtypes rests on how the lymphoblasts look under the microscope. L1 features are small, uniform lymphoblasts with scant cytoplasm and smooth, consistent nuclei. L2, on the other hand, has larger, more variable lymphoblasts with irregular nuclear contours and clefts or indentations in the nuclei. That nuclear clefting is the telltale sign that separates L2 from L1.

So, the distinguishing feature is nuclear clefting on the lymphoblasts. The idea is that L1 blasts are uniform and lack clefts, while L2 blasts show clear nuclear irregularities, including clefts. Auer rods point to myeloid lineage rather than lymphoid, so they wouldn’t differentiate L1 from L2. Erythroid precursor abundance isn’t a defining feature for these two lymphoblastic subtypes.

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