The document discusses the history, utility, and methods of preparing cell blocks from fine needle aspiration cytology samples. Cell blocks allow examination of histological structure and use of ancillary tests. Key methods include the fixed sedimentation method using a 1:1 ratio of 100% alcohol and 40% formalin, the plasma thrombin method using equal parts plasma and thrombin, and the bacterial agar method using 3% agar. Cell blocks provide increased diagnostic sensitivity and specificity compared to cytology alone through examination of tissue architecture and ability to perform special stains and molecular testing.

1. CELL BLOCK PREPARATION,
DIAGNOSTIC UTILITY AND ITS
RELEVANCE
Dr. Gaurav kumar
King Georges Medical University

2. History
• 1896- cell block prepared in celloidin embedding medium
• 1901- centrifugation was used to increase cellularity
• 1959- bacterial agar introduced for preparing cell block
• 1973- plasma thrombin clot introduced
• 2007- automated cell block system (cellient)

3. Fine needle aspiration cytology
(FNAC)
• FNAC is the study of cellular
samples obtained through a fine
needle
• It is useful in palpable lesions of
thyroid, lymph nodes, salivary
glands, breast and subcutaneous
tissues

4. • Relatively painless and inexpensive
• Provides unequivocal diagnosis (sensitivity and specificity ≥
90%)
• Highly suitable in debilitated patients and multiple lesions
• Low risk of complications
• Easily repeatable

5. FNAC/ Fluids
Cytosmears
CytosmearsBenign
CELL BLOCKS
Special stains ICC
Molecular
testing

6. • Cell blocks contain aspirated materials
embedded in paraffin that broaden the
diagnostic value of cytology specimens
and are complementary to cytology
preparations
• It employs retrieval of small tissue
fragments from FNA specimen which
are processed to form a paraffin block
What is a cell block ?

7. Cell blocks offer the opportunity to examine the
histological structure and allows the use of ancillary
tests
Cytology Histopathology
Bridge
(Cell blocks)

8. • Acquisition of tissue for cell block can increase both
diagnostic sensitivity and specificity (through both cellular
morphology and ancillary testing)
• It requires minimal effort and is cost efficient.
• Moreover, tissue preserved in cell block can be stored
easily
Need for Cell Block

9. Material required for cell block

10. Specimens
FNAC SPUTUM
EFFUSION FLUIDS
URINE
LAVAGES & WASHINGS

11. Salvaging of grossly visible flecks of tissue or Sediment
Fixation by formalin or any other fixative
Paraffin embedding
Cutting
Staining

12. 1. Fixed sediment method
2. Histogel method
3. Gelatin embedding
4. Bacterial agar method
5. Plasma thrombin method
6. Colloidion bag
Methods of cell block preparation
7. Scraping of cytology
smears
8. Cell blocks from Millipore
9. Automated preparation
10.Albumin method

13. Fixed sedimentation method
Take 100% alcohol : distilled water (1:1)
Put the aspirate in it
Centrifuge @1500rpm for 6 min
PELLET
100% alcohol + 40% formalin (9:1)
45 min stand
Centrifuge @1500rpm for 6 min
Pellet dislodge
Block

14. Histogel method
• Specimen remains surrounded by Histogel
• Can be used if very scant material is aspirated
• Better than agarose gel and thromboplastin
• Doesn’t retain stain particles

15. Histogel method

16. Plasma thrombin method
Equal amount of
plasma and
thrombin

17. Other methods
• Gelatin method- 2% molten gelatin is used
• Bacterial Agar method- 3% agar is used

18. Clot method
Aspirate 10% formalin
from the container in
which the specimen is
to be submitted for cell
block processing. This
dislodges the clot from
syringe wall.
Let the remaining aspirate
clot in the syringe for 5 to 7
minutes (slightly longer than
the clotting time).
Gently and firmly
remove the
plunger of the
syringe .
Transfer the
aspirated formalin
with dislodged clot
in to the specimen
container with 10%
formalin fixative

19. Automated cell block (cellient)

20. 1. Cell Block is simple , reproducible and readily available in
routine labs
2. Increased cellularity
3. Better morphological and architectural patterns
4. Additional yield of cells, thereby increasing diagnostic yield
5. Unlimited storage of the sample
6. Application of ancillary studies (ICC and molecular testing)
Advantages

21. Disadvantages of cell block
• Compared to routine smears takes longer time
• Distortion artifact

22. Cytosmears v/s Cell Block

23. Refrences
• G.W. Gill, cytopreparation: principles &
practice, essentials in cytopathology12,
Springer science
• Shidham & Epple Ch 14‘Cytopathologic
Diagnosis of Serous Fluids’ :Elsevier (W. B.
Saunders Company)
• Koss diagnostic and cytology and its
histopathologic bases 5th edition

24. Thank you

25. MCQ

26. 1- Most common method of cell block
preparation
a) Fixed sedimentation method
b) Plasma thrombin method
c) Agar method
d) Gelatin method

27. 2- % of alcohol and formalin in fixed sediment
method is-
a) 100% alcohol and 40% formalin
b) 90% alcohol and 40% formalin
c) 40% alcohol and 40% formalin
d) 40% alcohol and 100% formalin

28. 3- % of agar used in bacterial agar method-
a) 1%
b) 2%
c) 3%
d) 4%

29. 4- amount of plasma and thrombin used in
plasma thrombin method?
a) 1:1
b) 1:2
c) 2:1
d) 3:1

30. 5- Ratio of formalin(40%) and alcohol(100%) is-
a) 1:9
b) 9:1
c) 2:3
d) 3:2