Histochemistry and cytochemistry Flashcards
1
Q
Myeloperoxidase
A
- stains primary (azurophilic) granules of granulocytes/myeloblasts
- negative in lymphoblasts, erythroblasts, megakaryoblasts, most monoblasts (fine dusty positive may be seen), and very early blasts
- degrades quickly in wet specimens, but is stable in smears for up to 1 month
- because of rapid degredation, a negative MPO should not exclude AML
2
Q
Sudan black B
A
- stains lipid material present in granulocytic series
- reactivity parallels that of MPO
3
Q
Chloroacetate esterase
A
- also known as the Leder stain
- positive in granulocytes and mast cells
- can be positive in abnormal (neoplastic) eosinophils but negative in normal eos
4
Q
Nonspecific esterases (NSE)
A
- alpha naphthyl acetate esterase and alpha naphthyl butyrate esterease
- stain the monocytic series but nonspecific
- the NSE activity of monocytes is inhibited by sodium fluoride (NaF)
5
Q
PAS
A
- positive in most lymphoblasts with “block”/”rosary bead” pattern
- myeloblasts (??) may show diffuse, granular staining
6
Q
Oil red O
A
- stains vacuoles of Burkitt lymphoma/leukemia
7
Q
Leukocyte alkaline phosphatase
- biochemical reaction
- how is LAP score derived?
- normal LAP score
- CML LAP score
- other conditions with low LAP score
- high LAP score seen in
A
- hydrolyzes naphthol AS-biphosphate, component of neutrophil granules, to form a colored product
- LAP score is derived by visual examination of 100 bands and neutophils
- each cell scored on the basis of the intensity of cytoplasmic staining from 0 to 4+
- sum of the 100 values is the LAP score
- normal adults: LAP score between 40 and 120
- CML: 0-15
- other conditions with low LAP score:
- PNH
- some MDS
- congenital hypophosphatemia
- neonatal septicemia (paradoxical)
-
high LAP score:
- reactive neutrophilia
- PV
- PMF
- glucocorticoid administration
- 3rd trimester of pregnancy
