Cytochemistry

Question 1

MPO

Answer 1

• myeloid diff
• stains primary (azurophilic) granules
• faint positivity may be seen in monoblasts
• negative in non-myeloid blasts

Question 2

Sudan Black B (SBB)

Answer 2

• myeloid diff
• stains lipid material
• faint positivity may be seen in monoblasts
• negative in non-myeloid blasts

Question 3

Chloroacetate esterase (CAE)

Answer 3

-positive in granulocytes only

Question 4

Nonspecific esterases (NSE)

Answer 4

• Includes alpha-naphthyl acetate (ANA) esterase and alpha-naphthyl butyrate (ANB) esterase*
• monocytic and megakaryocytic lineages
• monocyte staining can be inhibited by sodium fluoride (NaF)

Question 5

PAS

Answer 5

• lymphoblasts: shows “block” positivity, often encircling the nucleus in a “rosary bead” fashion
• some myeloblasts: diffuse granular staining
• erythroblasts (neoplastic only)

Question 6

Acid phosphatase (AP)

Answer 6

-positive in megakaryoblasts and lymphoid cells (dotlike)

Question 7

Oil Red O

Answer 7

-stains vacuoles of Burkitt

Question 8

Leukocyte alkaline phosphatase (LAP)

Answer 8

• 100 bands and PMNs are counted and scored on the intensity of cytoplasmic staining from 0-4
• sum of 100 cells is the LAP score
• normal 40-120
• CML have decreased LAP score (0-15)
• other causes of low score: PNH, some MDS, congenital hypophosphatasia, neonatal sepsis
• elevated levels (greater than 100) seen in leukemoid rxn, non-CML MPNs, glucocorticoid tx, pregnancy

Question 9

AML M0

Answer 9

All negative

M0: minimal differentiation

Question 10

AML M1-M3

Answer 10

MPO, SBB, CAE

• M1: minimal differentiation*
• M2: with maturation*
• M3: APL*

Question 11

AML M4

Answer 11

MPO, SBB, CAE, NSE

M4: myelomonocytic-includes eosinophilia

Question 12

AML M5

Answer 12

NSE only

M5: monoblastic/monocytic

Question 13

AML M6

Answer 13

MPO, SBB, PAS

M6: erythroleukemia

Question 14

AML M7

Answer 14

PAS, AP, NSE+/- (mostly +ANA esterase, -ANB esterase)

M7: megakaryoblastic