This cytospin is from a case of acute monoblastic leukemia (AMoL) in a patient with central nervous system involvement.
These blasts are much larger than the blasts in the previous cases.
The morphology in this smear is consistent with the classification of M5a. M5a stands for "monoblastic without maturation," which is appropriate in this case since there are no promonocytes or monocytes present.
When a patient has an established diagnosis of M5b, abnormal promonocytes would be evident.
It is important to note that each individual patient's morphology will vary depending on the morphology of their original leukemia. If the patient relapses, the morphologies observed in both the cerebrospinal fluid and peripheral smears may become more extreme, since therapy selects for the most abnormal and resistant clones.