13
Respiratory Tract
Fig. 13.46 Cell showing changes of cytomegalovirus infection, including
an intranuclear inclusion with surrounding halo and peripheral margination
of the chromatin. Bronchial washing (Papanicolaou x OI).
Infection with adenovirus produces two types of intranuclear
inclusions in bronchiolar and alveolar lining cells. The first type
consists of a small red body surrounded by a well-circumscribed
clear halo. The second is a homogeneous basophilic mass
almost completely replacing the nucleus. Ciliocytophthoria may
be quite pronounced. The most characteristic cytologic finding
in measles pneumonia is the presence of multinucleated giant
cells containing eosinophilic inclusions that are present within
both the nucleus and cytoplasm.184,185 Respiratory syncytial virus
also stimulates a proliferation of multinucleated giant cells with
cytoplasmic basophilic inclusions surrounded by halos.
Bacterial infections
Although the majority of lung infections produced by bacteria
do not lend themselves to primary diagnosis by conventional
cytologic methods, in a few instances, the cytologic specimen
may be extremely helpful.
Gram-Positive and Gram-Negative Bacteria
It is not at all uncommon for specimens of sputum to show bac-
illary and coccal forms of bacteria. These rarely indicate pulmo-
nary infection but rather are the result of bacterial overgrowth.
Actinomyces
may be seen as contaminants from the tonsillar
crypts. Similar observations are also usually true for bronchial
material. In contrast, the presence of bacteria in a cytologic spec-
imen from an FNA may be of extreme importance. A striking
example is found in a 45-year-old physician-patient who had
pyoderma gangrenosum and hypogammaglobulinemia and
who developed several cavitary lesions in his left lower lobe. An
FNA specimen revealed the presence of many bacilli that were
Gram-negative and found on culture to be
Pseudomonas aerugi-
nosa.
We have also seen
Staphylococcus aureus
in the form of bot-
ryomycosis diagnosed by FNA. In evaluating such specimens, it
is important to remember that although the Papanicolaou stain
renders bacteria visible, their red or blue staining has no connec-
tion to true Gram-negative or Gram-positive findings.
Opportunistic infections with
Legionella pneumophila
and
Legionella micdadei
are worthy of note because they appear to
be increasing in frequency.186
Legionella
is an extremely small
Gram-negative rod. Specimens of sputum, bronchial mate-
rial, and particularly FNAs stained by the Dieterle method of
silver impregnation may reveal the organisms. Much greater
sensitivity in detection of this organism is being achieved by
immunofluorescence microscopy, however, using
anti-Legionella
antisera, which are now commercially available. Other bacteria
more recently described include
Rhodococcus equi187
and
Fuso-
bacterium nucleatum.188
Acid-Fast Bacteria
The search for acid-fast organisms in a cytologic specimen is
likely to be most useful for a patient with suggestive morpho-
logic evidence of granulomatous inflammation and necrosis or
an extremely suggestive clinical history. Patients infected with
Mycobacterium avium-M. intracellulare
complex may show large
alveolar macrophages, which on acid-fast stain reveal large
numbers of branching acid-fast bacilli.
Mycobacterium avium
complex infections have become the most common bacterial
infection in patients with AIDS.189 Cell blocks prepared from
FNA are useful for acid-fast staining when it is suspected that a
tuberculous lesion has been aspirated. Fluorescence microscopy,
with auramine O may also reveal the organisms. Maygarden and
Flanders reported the cytologic findings from three patients with
AIDS in whom mycobacteria were seen on the routine modified
Wright-stained slides without special stains.190 The organisms
appeared as negative images—unstained rod-shaped structures
against the deep blue background of the stain. Nocardiosis
should be suspected when FNA reveals the presence of delicate
branching filamentous rods with an inflammatory reaction con-
sisting mainly of neutrophils. Positive acid-fast stains further
enforce this diagnosis.191
Fungal infections
Many of the respiratory fungal infections are readily detectable
by cytologic methods. In these diseases, the etiologic agent is
visible and in some cases has a morphology on which a spe-
cific diagnosis may be based. The detection of these fungi in a
stained cytologic specimen may be the first clue to the nature of
a patient's problem. The accuracy of observation is dependent
on the ability of the cytologist to appreciate the various forms
that the fungi may assume.
Pulmonary Blastomycosis
Blastomycosis (North American blastomycosis, Gilchrist's dis-
ease) is a chronic infectious disease of both granulomatous and
suppurative types that may involve the lungs, skin, bones, and
genitourinary tract. It is caused by infection with dimorphic
fungus
Blastomyces dermatitidis.
The disease is endemic in many
parts of the United States, including the Ohio, St. Lawrence, and
Mississippi River valleys and the southeastern United States. It
has also been found in southern Manitoba, Mexico, and parts
of South America and Africa. The natural habitat of
B. dermati-
tidis
is believed to be the soil from which infectious conidia are
inhaled.192 The symptoms, signs, and changes seen radiologi-
cally may closely resemble the appearance and progression of
lung cancer. Symptoms may consist of cough, dyspnea, chest
pain, low-grade fever, weight loss, and weakness. The sputum
may become purulent or blood streaked. In well-developed
cases, the radiologic findings may include unilateral, dense,
irregular shadows, which may be produced by lung cancer,
hilar adenopathy, consolidation, or cavitation.193,194 Sputum
production may be present in 50-80% of patients and is usually
found to contain organisms.
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