20
Fine-Needle Aspiration Biopsy Techniques
Table 20.1 Comparison of Air-Dried and Wet-Fixed Smears
Air-dried smear
(Romanowsky stain)
Wet-fixed smear
(Papanicolaou
stain)
Dependence on
smear technique
Strong
Moderate
Dry smear
Good fixation
Drying artifacts
common
Wet smear
Artifacts common
Good fixation
Tissue fragments
Cells poorly seen,
heavy background
staining
Individual cells seen
clearly
Cell and nuclear
area sections
Exaggerated, differ-
ences enhanced
Comparable to tissue
Cytoplasmic detail
Well demonstrated
Poorly demonstrated
Nuclear detail
Different pattern from
Papanicolaou stain
Excellently demon-
strated
Nucleoli
Not always discernible
Well demonstrated
Stromal
components
Well demonstrated
and often differentially
stained
Poorly demonstrated
Partially necrotic
Poor definition of cell
Good definition of
tissue
detail
single intact cells
Table 20.2 Comparison of Staining Features between Romanowsky Stain
and Conventional Papanicolaou Stain
Features emphasized
by Romanowsky stain
Features
emphasized by
Papanicolaou stain
Epithelial
Mucin, intracellular, or
extracellular, colloid
(thyroid); secretory
granules (prostate); lipo-
fuscin granules (seminal
vesicles); lipid vacuoles;
fire flares (thyroid); bare
bipolar nuclei (benign
breast); bile plugs;
basement membrane
globules (adenoid cystic
carcinoma); amyloid.
Squamous
differentiation/
keratinization;
oncocytes (salivary
gland tumors);
psammoma bodies.
Lymphoid
Cytoplasmic basophilia;
Nuclear outline;
lymphoglandular bodies;
nuclear chromatin
hematopoietic cells; lipid
pattern; nucleoli.
vacuoles.
do not have to consider the details of fixation of smears. Rather,
the laboratory can decide which smears to stain by this rapid
Papanicolaou method and which to stain using other stains.
Ancillary Techniques and Applications
The use of nearly all of the special techniques that have evolved
for application to tissue specimens have been applied to aspira-
tion biopsies and other types of cytologic samples.31 They may
Fig. 20.3 Aspiration smears from solitary thyroid nodule. Clusters
and overlapping nuclei and nuclear enlargement and elongation suggest
papillary carcinoma. Nuclear grooves and intranuclear inclusions are not well
seen (Diff-Quik x MP).
Fig. 20.4 Aspiration smears from solitary thyroid nodule. Same case
as in Fig. 20.3, rapid Papanicolaou stain, available 90 seconds after the Diff-
Quik stained slides are ready for review. Note the same basic morphology
of the cell groupings, suggesting papillary carcinoma. Good examples of
intranuclear inclusions and nuclear grooves are easily seen, confirming the
initial impression from the Diff-Quik-stained smear of papillary carcinoma of
the thyroid (Rapid Papanicolaou x MP).
enhance the diagnostic capabilities. Immunoperoxidase stain-
ing can be performed directly on smears, on microcore-cell
block material, and on cytospin preparations of aspirates col-
lected in balanced salt solutions or RPMI, a cell transport media.
With the use of direct smears, background staining may be sig-
nificant, but if the cells in question are staining intensely, this
represents a positive reaction for the antibody in question. Iden-
tification of a terminally differentiated protein, such as gastrin
or prostatic-specific antigen, is quite reliable on direct smears.
Background staining can be ignored and is likely from the tar-
get protein displaced by rupture of the cells during smearing.
The basic differential between lymphoma and undifferentiated
carcinoma is also quite reliable when immunocytochemical
staining with CD45 versus a cytokeratin cocktail is applied to
direct smears. To obtain a clean background and in cases of lym-
phoproliferative disease, cytospin preparations (see Appendix)
usually provide a good differentiation of positive and negative
589
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