SPECIMENS FOR CELL BLOCK
• Body cavity effusion fluids,
• cyst contents,
• scraped material from aspirate slides or
• Millipore filters and LBC specimens can all be used for
the preparation of CBs.
1) Simple sedimentation technique (Drawback of
2) Normal saline needle rinse method :--
a) The commonly used
b) Rinse the aspiration needle with 20–30 ml of
normal saline, centrifuge immediately or preserve in RPMI
(Rosewell Park Medical Institute) medium for future
centrifugation, and collect the material for processing as
for a tissue biopsy.
3) TISSUE COAGULUM CLOT (TCC)
• To augment cellularity in CB sections,
• The TCC method is used, without diluting the
material by saline, allowing the clot of tissue and
blood mixture to form in the lumen of the needle.
• As the coagulum streams out from the needle tip, it is
collected onto a piece of filter paper and air dried.
• The clot is only slightly air dried in order to preserve
• The tissue coagulum is then transferred into a
formalin container and subsequently processed
• TCC is considered to be superior to a conventional
aspiration needle rinse in the recovery of cellular
• prevention of the loss of diagnostic material.
4) PLASMA THROMBIN OR THROMBIN
• A CB can be prepared from the pellet of any centrifuged
cell suspension by adding plasma and thrombin to
enmesh the cellular material in a clot
• Although the unpredictability of clot formation and clot
size in the plasma thrombin technique may cause an
uneven concentration of cells, one can overcome this
problem by the use of continuous agitation during clot
formation to disperse the cell population evenly
throughout the fibrin mesh.
• Some commercially available thromboplastin
reagents prepared from rabbit lung or brain contain
epithelial cells, which may lead to erroneous
interpretation of the case. Thus, cell-free
thromboplastin should be chosen for this method.
5) USE OF ADJUVANTS
• The difficulties in the recovery and processing of small tissue
fragments have resulted in alternative manual CB methods
which include the use of cell adjuvants, such as
C) Gelatin albumin
E) Pre-gelatinized starch
F) Sodium alginate
G) Gelatin foam,
H) Polyvinyl alcohol foam
I) Acetone-melted paraffin technique
J) Gelatin capsules.
• Principally, the concentrated sediments are supported by
a substance such as agar or a collodion bag .
• Agar solidifies below 50 °C, and this property of agar is
utilized to form the cell pellet.
• If the cellularity is scanty, it is advisable to perform the
collodion bag method. Collodion is a nitrocellulose
material, which is used to make blocks of friable tissue,
such as brain, in histology laboratories.
6) SHANDONTM CYTOBLOCKTM
• Second alternative manual CB preparation product.
• By design, it concentrates cells by cytocentrifugation in a
Thermo Shandon Cytospin using Cytoblock cassettes
and reagents available in the kit.
7) RAPID CB METHOD
• A new rapid CB technique has been used to improve the
accuracy of breast FNA even in sparse material.
• It increases overall cellularity with decreased time and fewer
• A proprietary tissue cassette and filter assembly is designed
to capture small tissue fragments and position them in a plane
• The rapid CB technique deposits the needle rinse material in
one plane, resulting in a higher yield of tissue fragments. This
technique has been further developed into the automated CB
system described below.
8) AUTOMATED CB PREPARATION
• The CellientTM system is the first fully automated CB
system and the most recent advance in this technology
• Cellient automatically recovers small tissue fragments
from a specimen container and rapidly delivers them in
paraffin for histological sectioning in less than an hour.
• The Cellient system works on vacuum-assisted filtration.
• visualization of abnormal cells, even when they are in
low concentrations, more efficiently than simple
sedimentation or HistoGel CBs
• Furthermore, it can be a useful technique to improve the
diagnostic accuracy of atypical glandular cells in
• Cellient CBs provide comparable results in
immunohistochemical determination, in situ hybridization
(ISH) and molecular analysis of breast cancer
biomarkers to those obtained using formalin-fixed and
1) CBs are increasingly being used as an adjunct to
smears to improve the diagnostic accuracy of FNA
• The sensitivity of CBs for FNAs varies from 60% to
approximately 90% depending on sampling type, size of
specimen and aspiration technique used.Overall
improvement and additional information for diagnosis
have been observed in 15–55% of cases.
• Using morphology alone, CB increases the detection
rate of malignancy by 6.5–9% when combined with
2) The cytological study of effusions is a routine
procedure and of great importance in the diagnosis
and management of patients.
In body fluid specimens, the results of smears and
CBs are almost identical in terms of diagnostic yield
3) The adjunctive use of a single CB slide with LBC
increased the detection rate of malignancy by 67%
over LBC alone, and the use of ancillary studies on
CB further improved the diagnostic accuracy and
4) The utility of CBs lies in the availability of diagnostic
material for further morphological examination,
histochemistry and ICC for better characterization of
In many circumstances, biopsy tissue is not available
and a cytological specimen may be the only source
available for molecular analysis.
1) Increased turnaround time.
2) Excess material is required to obtain a goodquality
cellular pellet, which is not always possible, especially
in deep-seated organs.
3) The risk of losing cytological material during tissue
processing or sectioning is another drawback because
of the small size of the specimen.
4) Not all specimens are suitable for CB preparation, and
a significant volume of CB preparations lack sufficient
tumour cellularity for future ancillary testing.
5) All CB techniques are labour intensive and demanding
6) Lastly, in comparison with traditional smear cytology,
the CB method adds an extra cost to patient management.