13
Respiratory Tract
%
1
^
x
Fig. 13.52
Candida
spp. Sputum (Papanicolaou x MP).
Pulmonary Paracoccidioidomycosis
Paracoccidioidomycosis (South American blastomycosis) is a
chronic systemic fungal infection caused by the dimorphic path-
ogen
Paracoccidioides brasiliensis.
The disease is largely confined
to Central and South America and has been reported in Mexico,
Brazil, Colombia, and Venezuela. Infection is believed to occur
through inhalation of fragments from the mycelial phase. Pul-
monary symptoms include cough, hemoptysis, dyspnea, fever,
malaise, and weight loss. Radiographic changes are nonspecific
and may include infiltrates, nodular densities, consolidation,
and cavitation.193 The yeast-like phase of the organism is present
in the infected tissue and may be seen in cytologic specimens
of sputum, bronchial material, BALs, and FNAs. The organisms
of paracoccidioides are highly characteristic and virtually diag-
nostic. In alcohol-fixed, Papanicolaou-stained cytologic speci-
mens, the fungus appears as an oval-to-round yeast, measuring
6-40 pm
in
diameter.
Multiple budding is
characteristic
and manifested by many buds attached by their necks to the
parent yeast. This appearance has been compared with that
of the pilot's wheel of a ship, with the tiny buds corresponding
to the handles of the wheel.
In a 1984 study, Tani and Franco, on review of respiratory
cytologic material from 45 patients with paracoccidioidomyco-
sis, were able to identify the organisms in more than 95% of the
patients.214
Pulmonary Aspergillosis
Pulmonary aspergillosis has been defined by Chandler and
Watts as a spectrum of pulmonary infections that includes aller-
gic reactions, fungal growth in a preexisting lung cavity, tracheo-
bronchitis, chronic destructive infection of the lung parenchyma,
and rapidly progressive fungal invasion of the parenchyma
and pulmonary vessels.193 The last is most likely in severely
immunocompromised patients.
The causative organisms, members of
Aspergillus
spp., are
found throughout the world. In descending order of frequency,
organisms responsible for infection are
Aspergillus fumigatus,
Aspergillus flavus,
and
Aspergillus niger.
Pulmonary aspergillosis
is acquired through the inhalation of the organism's airborne
spores. These spores are quite small, measuring less than 4 pm
in diameter, and are capable of reaching the most peripheral
parts of the lungs. Because exposure to
Aspergillus
spores is
a common event for all humans and aspergillosis is uncommon,
the immune state of the patient is probably the most significant
determining factor. The presenting signs and symptoms of a
patient with pulmonary aspergillosis depend on the underlying
disease and the type of
Aspergillus
infection.
We have observed
Aspergillus
spp. in cytologic specimens of
sputum (50% of cases), bronchial washings (23% of cases),
bronchial brushings (3% of cases), and FNAs (20% of cases).
Table 13.6 summarizes a sampling of the varieties of aspergil-
losis seen in our institution during the past 25 years.
The most characteristic presentation of the organism is that of
thick, uniform, septate hyphae 3-6 pm in width with 45°-angle,
brush-like branching (Fig. 13.53). The mycelial growth in pul-
monary aspergillosis is only rarely associated with the presence
of conidiophores or fruiting heads; thus, confusion with phyco-
mycosis may occur. However, fungi producing phycomycosis are
only rarely septate. The presence of septate, branching hyphae
in cytologic material is strong morphologic evidence of infec-
tion. Culture findings alone may be positive in the absence of
true infection. Conidiophores may occasionally be seen. The
morphology of these structures gives
Aspergillus
its name (i.e.
aspergillum—a brush or perforated globe for sprinkling holy
water). They expand into large vesicles at the end, the surfaces of
which are covered with sterigmata bearing long chains of spores
(Fig. 13.54). Their presence confirms
Aspergillus
spp. Intracavi-
tary fungus balls of the lung produced by
Aspergillus
as well as
other fungi may cause marked cellular atypias easily mistaken
for squamous cell carcinoma.17,215 Their presence may occasion-
ally be associated with the production of crystals of calcium
oxalate.216,217 Identification of oxalate crystals in the cytologic
specimen may be the first clue to the presence of
Aspergillus
.
These crystals as well as pigmented conidia are particularly
striking in infections with
A. niger.218
Pulmonary Mucormycosis
Pulmonary mucormycosis is an opportunistic infection pro-
duced by various fungi in the order
Mucorales.
It has also been
referred to as phycomycosis and zygomycosis. The most fre-
quent pathogen cultured from infected patients is
Rhizopus
spp.;
however, a number of other organisms have been reported.
These include
Mucor, Absidia, Rhizomucor, Cunninghamella,
Mor-
tierella,
Saksenaea
,
Syncephalastrum
, and
Apophysomyces.
All of
these organisms are ubiquitous in nature, and some are com-
monly seen as molds growing on bread, fruit, and other foods.
Infection may occur when a severely immunocompromised
or debilitated patient inhales the sporangiospores. Pulmonary
mucormycosis is most commonly observed in patients with
acute leukemia or lymphoma. It also occurs in the presence of
diabetes mellitus, anticancer chemotherapy, renal failure, and
severe burns. Infected patients present with fever and pulmo-
nary infiltrates that may progress to infarction and occasionally
cavitation. Infarction results because of the propensity of the
organism to invade through the walls of the pulmonary vessels
and thrombose their lumina.193
The cytologic diagnosis of mucormycosis is dependent on
the correct recognition of hyphal fragments. Regardless of which
organism is producing the infection, the infecting hyphal frag-
ments are quite similar. The hyphae may exhibit considerable
variation in size and shape. They may be quite large, varying
from 6-50 pm in diameter. Branching is at irregular intervals
and is usually at right angles. The hyphae are usually nonsep-
tate and coenocytic. The tendency of the hyphal fragments to
325
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