DOI:10.2214/AJR.05.1065
AJR 2006; 187:1248-1252
© American Roentgen Ray Society
High-Resolution CT Findings of 77 Patients with Untreated Pulmonary Paracoccidioidomycosis
Arthur Soares Souza, Jr.1,
Emerson Leandro Gasparetto2,
Taisa Davaus3,
Dante Luiz Escuissato3 and
Edson Marchiori2
1 Faculty of Medicine of São José do Rio Preto, São
José do Rio Preto, São Paulo, Brazil.
2 University of Rio de Janeiro, Rio de Janeiro, Brazil.
3 University of Paraná, Curitiba, Paraná, Brazil.
Received June 21, 2005;
accepted after revision September 29, 2005.
Address correspondence to E. L. Gasparetto, R Fernando Amaro 98, ap 61,
80050-020 Curitiba, PR, Brazil.
Abstract
OBJECTIVE. The objective of our study was to describe the
high-resolution CT findings of 77 patients with pulmonary
paracoccidioidomycosis (PCM) who had not yet been treated for PCM.
MATERIALS AND METHODS. The high-resolution CT scans of 77
consecutive patients with proven pulmonary PCM were reviewed by two chest
radiologists, and decisions regarding the CT findings were reached by
consensus. Seventy-one of the patients were men and six were women, with an
average age of 49 years. The criteria for interpretation of the
high-resolution CT scans are defined in the Fleischner Society's Glossary of
Terms.
RESULTS. The most frequent high-resolution CT findings were
ground-glass attenuation areas (58.4%), small centrilobular nodules (45.5%),
cavitated nodules (42.9%), large nodules (41.6%), parenchymal bands (33.8%),
areas of cicatricial emphysema (33.8%), interlobular septal thickening
(31.2%), and architectural distortion (29.9%). Most of these high-resolution
CT findings predominated at the periphery (53%) and posterior (88%) regions
involving all lung zones, with discrete predominance in the middle zones
(35%).
CONCLUSION. The high-resolution CT findings of patients with
pulmonary PCM who have not yet been treated consist of ground-glass
attenuation areas associated with small centrilobular nodules, cavitated
nodules, large nodules, parenchymal bands, and areas of cicatricial emphysema.
These abnormalities are usually distributed in the posterior and peripheral
regions of the lungs, with discrete predominance in the middle lung zones.
Keywords: chest • high-resolution CT • infectious diseases • lung diseases • pulmonary paracoccidioidomycosis
Introduction
Paracoccidioidomycosis (PCM) is the most frequent endemic systemic mycosis
in Latin America, particularly in Brazil, Argentina, Colombia, and Venezuela
[1,
2]. The infection is caused by
Paracoccidioides brasiliensis organisms, a dimorphic fungus that
grows as budding yeast in tissue and as yeast or mold in culture medium. The
disease is acquired by inhalation of infectious particles that reach the lungs
and develop the primary infection
[3]. Initially, the disease
presents with no significant symptoms, but some cases may progress to severe
pulmonary involvement [4,
5]. The lungs are the main
target organ of P. brasiliensis organisms, and infection of the lungs
is the leading cause of morbidity and mortality in patients with PCM
[1,
6,
7]. Active pulmonary
involvement and residual fibrotic lesions have been reported in 80% and 60% of
patients with PCM, respectively
[6].
High-resolution CT is frequently performed in the investigation of
pulmonary infections, including PCM
[4,
7-10].
However, the few studies that have investigated the high-resolution CT
findings of PCM included patients who had been treated for PCM before the CT
scans were obtained [4,
7,
8]. Those studies showed that
interlobular septal thickening, ground-glass opacities, nodules,
peribronchovascular interstitial thickening, and traction bronchiectasis were
the most common high-resolution CT features of PCM
[4,
7]. However, there are no
studies, to our knowledge, that have investigated the high-resolution CT
findings of patients with pulmonary PCM who had not been treated for PCM
before undergoing scanning. Recognition of CT patterns associated with
pulmonary PCM could help in the early diagnosis of PCM and in the institution
of a specific treatment for PCM, so lung damage caused by the disease can be
avoided.
The aim of this study was to present the high-resolution CT findings of 77
patients with pulmonary PCM who had not been treated previously for PCM.
Materials and Methods
This study retrospectively analyzed the high-resolution CT scans of 77
consecutive patients with proven pulmonary PCM who underwent high-resolution
CT at our hospitals. None of the patients had received any modality of
treatment for pulmonary PCM before undergoing CT. There were 71 (92.2%) men
and six (7.8%) women who ranged in age from 29 to 75 years (median, 49 years).
All patients were symptomatic, usually presenting with chronic cough, slowly
progressive dyspnea, and a low fever. The time that had elapsed between the
onset of symptoms and diagnosis of PCM infection ranged from 1 to 12 weeks
(median, 3 weeks; SD, 3.54 weeks). The diagnosis of P. brasiliensis
infection was made at bronchoalveolar lavage (n = 28), bronchial or
transbronchial biopsy (n = 24), or surgical lung biopsy (n =
25) (or a combination of these techniques).
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Fig. 1 —High-resolution CT scan at level of inferior lobes shows
interlobular septal thickening and multiple small centrilobular nodules, some
of which have tree-in-bud pattern, in 35-year-old man with pulmonary
paracoccidioidomycosis.
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Fig. 4 —High-resolution CT scan at level of inferior lobes shows
diffuse ground-glass opacities associated with areas of reduced parenchyma
attenuation in 37-year-old man with pulmonary paracoccidioidomycosis. In
addition, irregular interlobular septal thickening with architectural
distortion is identified.
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The CT scans were obtained at end-inspiration using a 1- or 2-mm
collimation at 10-mm intervals and were reconstructed with a
high-spatial-frequency algorithm (Somaton ART, Siemens Medical Solutions; and
Xvision, Toshiba). The images were photographed at mediastinal (width, 350-450
H; level, 15-25 H) and lung (width, 1,400-1,600 H; level, -600 to 800 H)
window settings.
The films were studied by two chest radiologists, and decisions regarding
the findings were reached by consensus. The following high-resolution CT
features were analyzed: air-space consolidation, ground-glass attenuation,
nodules (characterized as large [> 10 mm]; small [< 10 mm]
centrilobular; or random), cavitated nodules, "reversed halo
sign," tree-in-bud opacities, interlobular or intralobular septal
thickening, peribronchovascular or bronchial wall thickening, bronchiectasis,
parenchymal bands, architectural distortion, cysts, and areas of low
attenuation (cicatricial emphysema). Criteria for these findings are defined
in the Fleischner Society's Glossary of Terms
[9]. Each one of these findings
was analyzed concerning its distribution in the lung parenchyma (central,
peripheral, or both; anterior, posterior, or both; and upper, middle, or lower
zone or a combination of zones). Lymph node enlargement, pleural effusions,
and any other lung abnormalities were also studied.
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Fig. 5 —High-resolution CT scan at inferior pulmonary veins shows
multifocal ground-glass attenuation areas, nodules with halo sign, and
"reversed halo sign" at left lung in 55-year-old man with
pulmonary paracoccidioidomycosis.
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Fig. 6 —High-resolution CT scan at level of inferior pulmonary veins
shows random nodules with halo sign, cavitated nodules, and cavitated mass at
left inferior lobe in 57-year-old man with pulmonary
paracoccidioidomycosis.
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Results
All the patients in this study had abnormal findings on high-resolution CT
scans. The most frequent findings were ground-glass attenuation areas (58.4%,
n = 45), small centrilobular nodules (45.5%, n = 35),
cavitated nodules (42.9%, n = 33), large nodules (41.6%, n
=32), parenchymal bands (33.8%, n = 26), areas of cicatricial
emphysema (33.8%, n = 26), interlobular septal thickening (31.2%,
n = 24), and architectural distortion (29.9%, n = 23) (Figs.
1,
2,
3,
4,
5,
6,
7). Mediastinal lymph node
enlargement was seen in 10 patients and pleural effusions in two cases. The
most common high-resolution CT findings and their distribution are detailed in
Table 1.
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Fig. 7 —High-resolution CT scan at level of inferior lobes shows
multiple ground-glass attenuation balls, "reversed halo sign," and
cavitated nodule with halo sign at posterior region of right lung in
48-year-old man with pulmonary paracoccidioidomycosis.
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TABLE 1: Summary of the Most Common High-Resolution CT Findings in Patients with
Pulmonary Paracoccidioidomycosis and Their Distribution in the Lungs
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Patients with pulmonary PCM frequently present with several high-resolution
CT features, but a predominant high-resolution CT abnormality was defined in
each case. The most frequent predominant findings were ground-glass
attenuation areas (32.5%, n = 25), small centrilobular nodules
(15.6%, n = 12), large nodules (15.6%, n = 12), and the
reversed halo sign (6.5%, n = 5).
Abnormal high-resolution CT findings were predominant in the periphery of
the lungs in 53% of the cases, in the central and peripheral regions in 29.4%,
and in the central lung regions in 17.6% of the patients. Concerning the
anterior and posterior lung zones, most of the abnormalities predominated
posteriorly (88%, n = 15), and the remaining two (12%) involved
similar amounts of anterior and posterior lung regions. Finally, in 35% of the
cases, the features predominated in the middle lung zones; in 23%, in the
inferior; and in 6%, in the superior lung regions. The superior and middle
lung zones were similarly involved in 18% of the cases, as well as the middle
and inferior lung areas (18%).
Discussion
PCM, or South American blastomycosis, is an important systemic mycosis in
Latin America [2]. The most
severe endemic areas of PCM in the world are in the subtropical regions of
Brazil. In those endemic areas, PCM is estimated to affect up to 10% of the
population, being particularly prevalent in farm workers
[3,
4]. The etiologic agent, P.
brasiliensis, is an aerobic dimorphic fungus with an unknown habitat
[6]. The disease is acquired by
inhalation of infective particles that cause a self-limited inflammatory
parenchymal lung infection [5].
The initial lesion is similar to the primary complex of tuberculosis, and it
is controlled by natural defensive mechanisms or it progresses to symptomatic
disease. Following this primary complex, the fungus can spread by lymphatic or
blood circulation to the kidneys, spleen, liver, bone, adrenal glands, and CNS
[2]. The lung is the organ most
commonly affected (50-100%) and is the site of lesions associated with the
acute and chronic forms of infection
[2,
6].
Few studies have aimed to present the high-resolution CT findings of
patients with pulmonary PCM [4,
7,
8]. In addition, the authors of
those studies included in their series patients who had been treated for PCM
infection before the CT investigation. Muniz et al.
[4] analyzed 30 cases of
pulmonary PCM, including 16 patients who underwent CT after treatment for PCM
had been initiated. The most common high-resolution CT findings in that study
included interlobular septal thickening (96.7%), ground-glass opacities
(66.7%), nodules (60%), areas of cicatricial emphysema (56.7%), and bronchial
wall thickening (46.7%). Funari et al.
[7] studied the high-resolution
CT findings of the largest series of patients with pulmonary PCM, but those
authors included only four patients who had not been treated for PCM infection
before undergoing CT. The most common high-resolution CT features in that
study were interlobular septal thickening (88%), nodular opacities (83%),
traction bronchiectasis (83%), peribronchovascular interstitial thickening
(78%), areas of cicatricial emphysema (68%), and centrilobular nodular
opacities (63%). These findings showed a predominant bilateral and symmetric
distribution, affecting all lung zones.
The most frequent high-resolution CT findings in the present study were
ground-glass attenuation areas (58.4%, n = 45), small centrilobular
nodules (45.5%, n = 35), cavitated nodules (42.9%, n = 33),
large nodules (41.6%, n = 32), parenchymal bands (33.8%, n =
26), areas of cicatricial emphysema (33.8%, n = 26), interlobular
septal thickening (31.2%, n = 24), and architectural distortion
(29.9%, n = 23). Most of these high-resolution CT findings
predominated at the periphery (53%) and posterior (88%) regions involving all
lung zones, with discrete predominance in the middle zones (35%). Finally, the
most frequent predominant findings were ground-glass attenuation areas
(32.5%), small centrilobular nodules (15.6%), and large nodules (15.6%). These
patterns and their distribution are different from those reported by Muniz et
al. [4] and Funari et al.
[7]. These differences can
probably be attributed to two factors. First, those authors included in their
series patients who had been treated for PCM infection before undergoing CT.
The reticular pattern, mainly interlobular septal thickening, that was
frequently seen in those studies may be associated with the chronic form of
infection and sequelae, thus explaining why those findings were not
predominant in our series. Second, although both of the other studies analyzed
the high-resolution CT scans based on criteria defined in the Fleischner
Society's Glossary of Terms
[9], our study protocol was
more detailed, including findings that were recommended by the glossary of
terms but were not considered by the authors of the other studies.
Funari et al. [7] compared
the high-resolution CT findings of two groups of patients in their series:
those who received up to 3 months of treatment (n = 16) and those who
received more than 3 months of treatment (n = 25). Although this
could correct the bias of their study, which included treated and nontreated
patients, Funari et al. added four patients who had not received treatment
before CT to the group of patients who had received up to 3 months of
treatment. The comparison was performed using Fisher's exact test, and
p values less than 0.05 were considered statistically significant.
The patients who had received less than 3 months of treatment were more likely
to present with areas of ground-glass attenuation (p = 0.02),
air-space consolidations (p < 0.01), and cavitations (p
< 0.01). Comparing our results with those of that study
[7], we observe that our
findings are more similar to those seen in the group of patients who had
received up to 3 months of treatment than those seen in the group who had
received more than 3 months of treatment. Parenchymal bands and architectural
distortion, although common in our study, were not predominant features,
probably indicating that these findings are more frequently representative of
chronic pulmonary PCM.
In conclusion, our study shows that the most frequent high-resolution CT
findings in patients with pulmonary PCM who had not yet been treated for PCM
infection include ground-glass attenuation areas, small centrilobular nodules,
cavitated nodules, large nodules, parenchymal bands, and areas of cicatricial
emphysema. Most of these high-resolution CT findings predominated at the
periphery and posterior regions, involving mainly the middle lung zones. In
addition, ground-glass attenuation areas, small centrilobular nodules, and
large nodules were the most common predominant high-resolution CT findings in
our series. Therefore, we believe that, in the appropriate geographic areas,
the diagnosis of PCM should be suggested in patients presenting with these
pulmonary CT features so that therapy for the infection can be initiated and,
thus, lung damage can be avoided.
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Abstract
Introduction
