Molekulare Marker

 1. AEG Tumors 

    a. in metastastic disease - MSI-H/d-MMR (ICI), Her2+/neu (Trastuzumab), PDL-1 CPS/TAP (ICI), Claudin 18.2 (Zolbetuximab)

    b. in Stadium IB-III, off-label use possible - Her2+/neu, PD1-PDL-1 CPS/TAP

Scores for PDL-1 Expression

1. Tumor Proportion Score (TPS): 

The percentage of viable tumor cells showing partial or complete membrane staining for PD-L1, relative to all viable tumor cells in the sample.

Formula:

$$\text{TPS} = \frac{\text{PD-L1 positive tumor cells}}{\text{total viable tumor cells}} \times 100\%$$

Interpretation example: TPS 10% → 10% of tumor cells express PD-L1.

2. Combined Positive Score (CPS):

The number of PD-L1–staining cells (tumor cells + lymphocytes + macrophages) divided by the total number of viable tumor cells, multiplied by 100.

Formula:

$$\text{CPS} = \frac{\text{PD-L1 positive tumor cells + PD-L1 positive immune cells}}{\text{total viable tumor cells}} \times 100$$

Interpretation example: CPS 20 → there are 20 PD-L1–positive cells (tumor + immune) for every 100 tumor cells.

3. Tumor Area Positivity (TAP):

The percentage of the total tumor area (tumor cells + associated stroma) showing PD-L1–positive staining, regardless of cell type. Measures area, not cell count.

Formula:

$$\text{TAP} = \frac{\text{PD-L1 positive area (tumor + stroma)}}{\text{total tumor area}} \times 100\%$$

Interpretation example: TAP ≥ 10% → at least 10% of the tumor area (tumor cells or immune cells) is PD-L1–positive.

Bone Marrow Smear - How to Interpret

Systematic Approach: 

1. Adequacy -  A good smear shows fat, spicules, and cellular material.

2. Cellularity - Compare hematopoietic cells to fat spaces.

Age-related norms: Cellularity ≈ 100 – age (±10%) (e.g., 40-year-old → ~60% cellularity).

- Hypocellular (e.g., aplastic anemia, marrow suppression).

- Hypercellular (e.g., leukemia, myeloproliferative disorders).

3. E:M/ ratio: erythroid precursors : myeloid precursors ≈ 1:2 to 1:4

- E:M ↑Erythroid Hyperplasia: hemolysis, thalassemia

- E:M ↓Myeloid Hyperplasia/Erythroid Hypoplasia: infections, CML, myeloproliferative neoplasms

4. Erythropoesis:

- Maturation steps: Proerythroblasts → basophilic normoblasts → orthochromatic normoblasts.

- Abnormalities:

Dyserythropoiesis: multinuclearity, nuclear budding, irregular chromatin.

Increased erythropoiesis: hemolytic anemias, blood loss.

Decreased erythrpoiesis: aplastic anemia, marrow infiltration.

5. Myelopoiesis/Granulopoiesis: 

- Maturation stages: myeloblasts → promyelocytes → myelocytes → metamyelocytes → bands → neutrophils.

- Look for:

Left shift (immature forms) → infections, leukemias.

Dysgranulopoiesis: hypolobation, hypogranularity.

Blasts >20% = acute leukemia (per WHO).

6. Megakaryopoesis: Normally present in small numbers, large cells with multilobed nuclei.

- Look for:

Increased: myeloproliferative neoplasms (e.g., essential thrombocythemia).

Decreased/absent: aplastic anemia, marrow failure.

Dysplastic forms: micromegakaryocytes, separated nuclei → myelodysplastic syndrome (MDS).

7. Other Cells

- Plasma cells: normally <5%. Increased in plasma cell disorders (e.g., multiple myeloma).

- Lymphocytes: scattered, small.

- Histiocytes/macrophages: may be seen with hemophagocytosis.

- Mast cells: few normally, increased in mastocytosis.

8. Special Features

- Blasts: count percentage (critical for leukemia diagnosis).

- Fibrosis: suggested if “dry tap” on aspiration → confirmed by biopsy.

- Infiltration: metastatic tumors, storage diseases (e.g., Gaucher cells).

- Iron stores (on Prussian blue stain)

a. Normal, increased (anemia of chronic disease), decreased (iron deficiency).

b. Ring sideroblasts → sideroblastic anemia, MDS.

Blood Cell Smear - How to Interpret

 Systemic approach:

Red Cells

1. Agglutination? - Hemolysis

2. Rouleux (Stacking)? - Indicative of Paraproteinemia (MM)

3. Nucleated Red Blood Cells? - Hemolysis/Bone marrow stress

4. Polychromasia (Increase in Reticulocytes) -Hemolysis/Blood loss (Increased Demand)/Response to Treatment (Ironsubs. in Iron Def. Anemia)

5. Quantity/Size - MCV, Anisocytosis?

6. Quality - Poikilocytosis 

7. Red Cell Inclusions - 

a. Howell jolly bodies (un-removed nucleus parts/Hyposplenism); normal in neonates; hemolysis and megalobastic anemia 

b. Basophilic stippling (ribosomal RNA; best seen in Reticulocytes) - Hemoglobinopathy, MDS, Heavy Metal poisoning (Lead)

c. Pappenheimer bodies (Hemosiderin granules) - Postspelenectomy, Iron-overload, Sideroblastic anemia

d. Malaria

White Cells:

1. Quantity: estimate the Count, Differential

2. Quality: check, Nucleus+Cytoplasma - reactive?dysplasia?malignant population?

a. pleomorphic (reactive) vs monomorphic (malignant)

b. size - small/mature (as lymphocyte), medium (as monocyte), large/immature (as promyelocyte), 

c. Nucleus to cytoplasma ratio (N/C) - high, moderate

d. Nucleus - immature/open/uncondensed/see-through chromatin (blasts) - mature/condensed chromatin/opaque (mature cells); cleft(visible groove)/cleaved(divided)/overlapping/indented -nucleus

e. Cytoplasma

 - color: clear, pale grey (monocyte); faint basophilic (lymphocyte), deep basophilic (plasma cells)

- inclusions: granules, vacuoles, auer rods?

f. company? - other cytopenias/dysplasia/rouleaux/leukoerythrombastic/tear drops?

g. Lymphocytes - reactive/atypical (pleomorphic + abundant cytoplasma) vs malignant (monomorphic, high N/C)

h. Neutrophiles:

- toxic neutophilia: left shift, toxic granulation, toxic vacuolation, dohle bodies, WC count < 40

- hypo-/hypergranulation

- segments (normal 3-4 sausage like, joined by narrow bridge): hypersegmented (Medication - Hydroxycaramid, MTX; B12/Folic acid deficiency, Dysplasia, rarely Iron Deficiency), hyposegmented (such as pseudo-pelger-huet - Dysplasia) and Tacrolimus.

Platelets: 

1. Quantity - estimate the count, 

2. Quality - size variation, granulation

Online Resources

Preparation: 
1. NEJM Rotation Prep Oncology and NEJM Rotation Prep Hematology (Subscription necessary)
2. Amboss (Subscription necessary)
3. ASH

4. The Blood Project 

Guidelines/'Look up':
1. Onkopedia (Guidelines from Germany/german speaking countries)
2. Uptodate (Subscription necessary)
3. Medscape (Professsional account necessary)

Cytology/Immunophenotyping:                                            Videos:

1. Ehaematology (Account necessary)                                  1. Saudi Blood
2. Onkodin
3. Society for Hematopathology
4. Pathology Outlines 
5. University of Utah
6. Utah
7. American Society of Hematology

8. Learn Haem

9. Virtual Lab Leed

10. Leed (with cases)

11. Blood Academy

12. Learn Haem

13. BHS

14. SH

15. Coursera

16. ISLH

17. Microscopic Hematology

Infectious Disease:

1. Infektopedia (in German)

Therapy-Protocols:

1. Hemonc

2. Onkopedia