Page 178 - Clinical Hematology Atlas

162 SECTION FOUR LEUKOCYTES

ACUTE MEGAKARYOCYTIC LEUKEMIA
FAB M7

A B
FIGURE 15–10A Peripheral blood (3500). FIGURE 15–10B Peripheral blood (3500).

Large atypical platelets with irregular borders
Hypogranular neutrophils
Bone Marrow: Usually results in dry tap
$20% blasts
$50% of blasts are megakaryoblasts
Two types of blasts may be present:

Small blasts: resembling lymphoblasts, round
nucleus, dense chromatin, scanty cytoplasm
Large blasts: fine nuclear chromatin, nucleoli,
cytoplasm abundant, basophilic, agranular,
6 pseudopods
CYTOCHEMISTRY
Myeloperoxidase: negative
Sudan Black B: negative
C Specific Esterase: negative
FIGURE 15–10C Micromegakaryocyte. Peripheral Periodic Acid–Schiff: positive or negative
blood (31000). Nonspecific Esterase: focal positivity
GENETICS
MORPHOLOGY Recurrent genetic abnormalities: not defined
Peripheral Blood: Blasts with abundant, budding NOTE: In infants may be associated with t(1:22)
cytoplasm (p13;q13).
Micromegakaryocytes 6 (see Figures 15-10, C IMMUNOPHENOTYPE
1
1
and 18-3, E) CD41 , CD61 , CD36 1