Diagnostic Cytology
Transbronchial Fine-Needle Aspiration
Transbronchial FNA as described by Tsuboi and associates,61
Hayata,62 Rosenthal and Wallace,63 and Horsley and associates64
is a special modification of needle aspiration for those cases in
which the lung neoplasm has not invaded through the mucosa
into the bronchial lumen and thus is not accessible through
sputum or bronchial brushing. This procedure involves insert-
ing a flexible needle through the fiberoptic bronchoscope, pen-
etrating the bronchial wall, and aspirating cytologic material
lying beyond.
In a reported study, Wagner and associates65 found an accu-
racy rate of 56% for transbronchial aspiration as compared with
48% for wash, 56% for brush, 35% for sputum, and 71% for
forceps biopsy all in the same patients. With this procedure,
Roche and associates reported an increased sensitivity when a
cytopathologist was present.66 DeCastro and colleagues reported
in 95 patients an overall sensitivity of 65.8%.67
In the diagnosis of lymphangitic spread of carcinoma, as an
alternative to transbronchial FNA, Masson and associates have
reported success with blood drawn through a wedged pulmo-
nary artery catheter.68
In the preparation of the cellular specimen from an FNA, the
most important principle is that the diagnostic cellular material
should be within the barrel of the needle and not within the
barrel of the syringe. To ensure that this relationship remains
undisturbed, the needle should be disconnected from the
syringe, the syringe refilled with air, and the syringe and needle
reconnected. One now is in a position to expel the contents of
the needle onto a slide or into a small amount of any solution
desired. Excellent smears are simply prepared by gently laying
one slide over the slide holding the drops of expelled material,
permitting the weight of the upper slide to spread the material,
pulling the slides apart horizontally and quickly dropping them
into 95% ethyl alcohol.
At our institution, the following procedure is followed. A 22-
gauge Chiba needle with a 20-mL syringe is inserted percutane-
ously into the lung mass. From the aspirate, two direct smears
are prepared for immediate wet fixation in 95% ethyl alcohol
and staining with the Papanicolaou method. The remaining
aspirate is then mixed with 10 mL of a balanced salt solution
and brought to the laboratory for further procedures. The cel-
lular suspension is centrifuged, and aliquots are processed for
membrane filters, direct smears, cytocentrifuge specimens, and
cell blocks. For immediate consultation, a drop of concentrated
suspension is mixed on a glass slide with a 0.4% aqueous solu-
tion of toluidine blue, and a coverslip is placed.
This simple preparation provides excellent nuclear detail,
but like other aqueous stains, it does not lend itself to perma-
nent storage. By this procedure, the radiologist can be given an
immediate assessment of the cellular content of the aspirate
and therefore an implied assessment of whether it is satisfac-
tory for diagnosis. If it is determined to be hypocellular, the
aspiration can be repeated immediately. When extensive necro-
sis is observed, the radiologist is advised to obtain additional
material from the periphery of the nodule, where well-preserved
tumor cells are more likely to be found. The presence of bacteria,
fungi, or inflammation is reported immediately to the radiolo-
gist so that appropriate cultures may be obtained. Based on the
findings in the wet preparation, the specimen can be evaluated
for additional cytochemical or immunocytochemical stains or
for electron microscopy.
Anatomy and Histology
The respiratory system has a number of known functions that
include cleansing and warming of inspired air, gaseous exchange
between the alveoli and capillaries, immunologic and cellular
host protection mechanisms, voice production, and olfaction.
As with other organ systems, it probably has a number of addi-
tional important functions yet to be discovered. The gross and
microscopic anatomy of the respiratory system is a remarkable
example of a structure designed for maximum efficiency in car-
rying out a series of complex functions. The anatomy relevant to
clinical cytology is discussed here.
A pair of lungs composed of many microscopic air sacs, the
alveoli, promotes the exchange of oxygen and carbon dioxide
with the capillary blood. A series of tubes, first bronchioles and
then bronchi, converging to form the trachea, connect the alve-
oli to the upper respiratory tract and, ultimately, through the
nose and oral cavity to the external environment. Each lung is
enclosed in a sealed expansile cavity surrounded by bone and
muscle. Through the action of these diaphragmatic and intercos-
tal muscles, those cavities or cages expand and contract to suck
air into the alveolar spaces and to expel its altered contents back
out to the exterior of the body.
The oral cavity and portions of the pharynx and nose are
lined by a nonkeratinizing stratified squamous epithelium. A
less thick squamous epithelium covers the vocal cords. Although
the morphologic examination of specimens from these areas
does not constitute a component of the discipline of respira-
tory cytology, superficial and intermediate squamous cells are
constantly exfoliating and consequently are commonly present
in sputum and bronchial specimens.
The major portions of the upper and lower respiratory tracts
are lined by a pseudostratified and ciliated columnar epithe-
lium (Figs 13.1 and 13.2). This mucosa covers the surfaces of
portions of the nasal cavities, the sinuses, and portions of the
larynx and the tracheobronchial tree. In histologic sections, this
epithelium may show two or three layers of nuclei, but each
cell is anchored into the basement membrane. Nestled between
these cells and adjacent to the basement membrane are small
round-to-polygonal cells believed to represent basal or reserve
cells. Mucus-producing goblet cells may be seen between the
ciliated cells (Figs 13.3 and 13.4). Their number is variable and
dependent on the absence or presence of environmental irritants
and certain diseases. Two rare cell types include brush cells, of
unknown function, and argyrophil or Kulchitsky-like cells.
As the terminal bronchioles are approached, the lining
epithelial cells begin to change. Ciliated cells, although still
present, are less numerous (Figs 13.5 and 13.6). Nonciliated
Clara cells become numerous with some projecting plump pro-
toplasmic protrusions into the lumen. These cells are believed
to have a number of important functions, including secretion of
the hypophase material of surfactant, detoxification of inhaled
toxic substances, and cellular reparative functions. Goblet cells,
normally not present, may be found in the bronchiolar epithe-
lium of smokers.
The alveoli are lined by an epithelium composed of two cell
types (Fig. 13.7). The type I cells or pneumocytes are long and flat-
tened and line more than 90% of the alveolar surface. The type II
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