Different hematopoetic cells stain differently with PAS stain. Let’s look at various PAS staining patterns in hematopoietic cells.
Pattern of PAS staining- Hematopoietic cells- CONTENTS
- Myeloid precursors and neutrophils
- Monocytes and it’s precursors
- Erythroid precursors and red blood cells
- Megakaryocytes and Platelets
- Lymphocytes and lymphoblasts
- Eosinophils and Basophils
1. MYELOID PRECURSORS AND NEUTROPHILS
Myeloid precursors show diffuse PAS positivity
Neutrophils show intense granular positivity
2.MONOCYTES AND THEIR PRECURSORS
Monocytes and their precursors show variable diffuse positivity.
3.ERYTHROID PRECURSORS AND RED BLOOD CELLS (RBCs)
Red blood cells are PAS negative
Erythroblasts show globular /granular PAS positivity
Normoblasts show diffuse PAS positivity
4. MEGAKARYOCYTES AND PLATELETS
Megakaryocytes and platelets are diffuselt PAS positive.
5. LYMPHOCYTES AND LYMPHOBLASTS
Lymphocytes show granular PAS positivity
Lymphoblasts show Block positivity
6.BASOPHILS AND EOSINOPHILS
Both basophils and eosinophils are negative for PAS
6 KEY POINTS TO REMEMBER FOR BOARDS – ACUTE LYMPHOCYTIC LEKUKEMIA- t(5;14)
- Basts harbour a translocation between IL3 and an IGH gene, resulting in variable eosinophilia
- This diagnosis can be made on the basis of immunophenotypic and genetic findings even if the bone marrow blast count is low.
- patients may present with an asymptomatic eosinophilia,
- Blasts may be deceptively absent in the peripheral blood.
- Eosinophils are a reactive popula tion and not part of the leukaemic clone.
- The prognosis is not considered to be different from that of other types of ALL
Click below for a summary
Answer this review question on ALL with the t(5;14)
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Differences between hypergranular (M3) and microgranular (M3v) variants of acute promyelocytic leukemia ( APML)
Acute Promyelocytic leukemia is an unique syndrome different from other forms of acute myeloid leukemia (AML).
From clinical symptoms such as disseminated intravascular coagulation (DIC) to unique chromosomal translocation – t(15;17) the list is endless.
Acute promyelocytic leukemia has two common variants- hypergranular (M3) and microgranular (M3v). It is essential to differentate the two variants because of prognostic purposes.
Let’s see a few key 🔑 differences between them.
1.White blood cell counts
M3v, that is the microgranular variant has a higher white blood cell count compared to hypergranular variant (M3).
2. Shape of the nucleus
M3v or the microgranular variety has a bilobed/butterfly shaped nucleus. The hypergranular variant has round to oval nucleus.
3. Auer rods
Auer rods may be present in M3v, but is very less compared to those present in the hypergranular variant. As the name suggests, hypergranular variant has large densely packed granules.
HLA-DR and CD34 are often positive in the microgranular variant in contrast to the hypergranular variant.
5. Associated mutations
M3v- microgranular variant is associated with FLT3-ITD mutations whereas, the hypergranular variant (M3) is not associated with FLT3-ITD mutations.
Why should you differentiate?
Presence of high white blood cell counts and FLT3-ITD mutations garner a poor prognosis, hence it is necessary to distinguish between hypergranular variant of APML and microgranular variant of APML.
Watch the video for quick summary-
Acute myeloid leukaemia (AML) with mutated NPM1 carries mutations that usually involve exon 12 of NPM1. Here are some key points to remember.
1. There is a female predominance in this type of AML.
2. There is a strong association between both acute myelomonocytic and acute monocytic leukaemia and NPM1 mutation.
3. Charactistic cup-shaped blasts are seen.
4. Immunophenotype: AML with mutated NPM1 is character ized by high CD33 expression and variable (often low) CD13 expression.
5. Immunophenotype: KIT (CD117), CD123, and CD110 expres sion are common.
6. Immunophenotype: HLA―DR and CD 34 is often negative.
7. Two major subgroups of AML with mutated NPM1 have been described: one with an immature myeloid immunophenotypic profile and one with a monocytic (CD36+, CD64+, CD14+) immunophenotypic profile.
8. Immunohistochemical detection of cytoplasmic NPM1 is predictive of NPM1 mutations. Remember that normally NPM-1 is expressed as nucleolar positivity.
9. Cases with a normal karyotype, in the absence of FLT3―ITD mutation, have a characteristically favourable prognosis.
10. Co-occurrence of NPM1, FLT3-ITD, and DNMT3A muta tions has been associated with a particularly poor outcome.
Hope you remember these key points for your boards!