DOI:10.2214/AJR.07.2161
AJR 2008; 191:247-251
© American Roentgen Ray Society
CT Differentiation of Anthracofibrosis from Endobronchial Tuberculosis
Hyun Jin Park1,
Seog Hee Park1,
Soo Ah Im1,
Young Kyoon Kim2 and
Kyo-young Lee3
1 Department of Radiology, Kangnam St. Mary's Hospital, College of Medicine,
Catholic University of Korea, 505 Banpo-dong Seocho-gu, Seoul, 137-040, South
Korea.
2 Department of Internal Medicine, Kangnam St. Mary's Hospital, College of
Medicine, Catholic University of Korea, Seoul, South Korea.
3 Department of Pathology, Kangnam St. Mary's Hospital, College of Medicine,
Catholic University of Korea, Seoul, South Korea.
Received March 2, 2007;
accepted after revision January 7, 2008.
Address correspondence to S. H. Park
(parksh{at}catholic.ac.kr).
Abstract
OBJECTIVE. The purpose of this study was to use CT to differentiate
anthracofibrosis from endobronchial tuberculosis (TB), both of which are major
causes of benign bronchostenosis.
MATERIALS AND METHODS. We retrospectively reviewed the clinical and
CT findings of 49 patients with anthracofibrosis and 35 patients with
endobronchial TB diagnosed on the basis of bronchoscopic, microbiologic, and
pathologic findings. Forty-five patients with anthracofibrosis and 32 patients
with endobronchial TB had bronchostenosis on CT and were enrolled in the
analysis. Nine (20%) of 45 patients with anthracofibrosis had coexistent
active TB (two, endobronchial TB; six, pulmonary TB; one, TB pleurisy), and 13
(29%) had pulmonary infections other than TB. Two patients with
anthracofibrosis and coexistent endobronchial TB were excluded from the
analysis. The CT findings were analyzed with emphasis on the pattern,
distribution, and location of bronchostenosis and the number of pulmonary
lobes involved.
RESULTS. Anthracofibrosis was more common than endobronchial TB
among elderly patients (p < 0.05). Statistically significant
findings on CT were the pattern of bronchostenosis, presence of main bronchus
involvement, and number of pulmonary lobes involved (p < 0.05).
Bronchostenosis with anthracofibrosis usually involves multiple lobar or
segmental bronchi. The main bronchus, however, tends to be preserved in
anthracofibrosis. Most cases of endobronchial TB involve one lobar bronchus
and the ipsilateral main bronchus with contiguity in extent.
CONCLUSION. Anthracofibrosis can be differentiated from
endobronchial TB on CT. Furthermore, CT is helpful in the diagnosis of
anthracofibrosis before bronchoscopy is performed.
Keywords: anthracofibrosis • bronchostenosis • CT • tuberculosis
Introduction
Bronchial anthracofibrosis is a bronchoscopic finding, defined as
bronchostenosis associated with anthracotic pigmentation without a relevant
history of pneumoconiosis [1].
The CT findings have been reported to include smooth bronchostenosis and
peribronchial lymph nodes along with peripheral atelectasis
[2–4].
Bronchogenic carcinoma and endo bronchial tuberculosis (TB) are two major
causes of bronchostenosis that can be ac companied by peribronchial nodes and
atelectasis [5,
6]. Bronchogenic carcinoma is
known to be easily differentiated from anthra cofibrosis, which usually
manifests as an endobronchial mass in a single lobar or segmental bronchus
[2]. In contrast to the study
of carcinoma, there has been, to our knowledge, no comparison study of the
relation between anthracofibrosis and endo bronchial TB. Therefore,
differentiation of anthracofibrosis from TB has been difficult. Because of the
similar CT findings, endobronchial TB has been suggested as a mech a nism
underlying anthracofibrosis
[1–4].
In addition to the radiologic resemblance, a high incidence of the coexistence
of TB and anthracofibrosis and a high prevalence of anthra cofibrosis among
women support this relationship
[1–4].
For these reasons, Chung et al.
[1] reported that empiric
anti-TB medication may be helpful in the treatment of anthracofibrosis
patients without evidence of active TB.
We evaluated whether CT can be used to differentiate anthracofibrosis from
endobronchial TB. Distinctive CT features of anthracofibrosis can help
radiologists diagnose anthraco fibrosis with ease before bronchoscopic
evaluation and can be a rationale negating the hypothesis that endo bronchial
TB is a major cause of anthra co fibrosis. To our knowledge, this study is the
first comparison of the CT findings in these two diseases.
Materials and Methods
We reviewed the CT scans of 49 patients with anthracofibrosis diagnosed on
the basis of bronchoscopic criteria, including anthracotic pigmentation and
bronchostenosis, over 3 years (July 2003–April 2006). Forty-one (91%) of
the 45 patients had bronchostenosis on CT. The other four were excluded from
analysis. None of the patients had an occupational history of exposure to
mining or industry. Thirty-four (76%) of the patients did not smoke. Six (13%)
of the patients had a history of pulmonary TB, and four of the six took
anti-TB medication.
All 45 patients with anthracofibrosis underwent bronchoscopy with bronchial
washing and brushing, and 23 (51%) of the 45 underwent biopsy. The biopsy
specimens exhibited chronic nonspecific inflammation (n = 22) and
edema with mononuclear cell infiltration (n = 1). Broncho scopic
biopsy revealed coexistent endobronchial TB in two patients with
anthracofibrosis. These two patients were excluded from the statistical
analysis. Two patients with anthracofibrosis underwent pulmonary lobectomy.
Four lymph nodes were dissected after lobectomy in one patient. All lobectomy
specimens revealed anthra cotic pigmentation with focal fibro sis of bronchi.
Dissected lymph nodes proved to have reactive hyperplasia with anthracotic
pigmentation.
CT scans of 35 patients with endobronchial TB were available. Thirty-two
(91%) of the 35 patients had CT findings of bronchostenosis and were enrolled
in the analysis. Fourteen (40%) of the 35 cases of endobronchial TB were in
the active inflammatory phase with acid-fast bacilli. The other cases were in
the chronic state, and the patients had been treated for active endobronchial
TB. The diagnoses of endobronchial TB were based on bronchoscopic,
microbiologic, and pathologic findings.
Both the anthracofibrosis and endobronchial TB groups of patients underwent
CT before bronchoscopy. Two CT scanners (Volume Zoom, Siemens Medical
Solutions; LightSpeed, GE Healthcare) were used. All scans were reconstructed
into axial images with 5-mm slice thickness at 5-mm intervals. Both unenhanced
and contrast-enhanced images were obtained. Two chest radiologists
retrospectively reviewed the CT scans, and a consensus diagnosis was reached.
CT findings were analyzed with emphasis on bronchostenosis. The pattern of
bronchostenosis was analyzed with a focus on a smooth or irregular
endobronchial contour. The number of pulmonary lobes with broncho stenosis was
recorded. Main bronchus involvement and bilaterality of bronchostenosis in the
two groups were assessed. Concomitant lymphadeno pathy and pulmonary lesions
were included in the analysis. Enlarged nodes greater than 1 cm in short-axis
diameter were defined as lympha denopathy. Student's t and Pearson's
chi-square tests were used for statistical analysis.
Results
Thirty-four women and nine men (median age, 76 years; range, 56–90
years) had anthracofibrosis; 24 women and eight men (median age, 51 years;
range, 19–80 years) had endobronchial TB. There were more women than men
in both groups. The anthracofibrosis group had a higher mean age than the
endobronchial TB group (p = 0.000, Pearson's chi-square test).
Twenty-seven (63%) of 43 patients with anthra cofibrosis had concomitant
disease at the time of diagnosis. Most of the concomitant disease was
reactivated TB (nine cases, 33%) and pneumonia (13 cases, 48%). The CT
features and location of disease are summarized in Tables
1 and
2.
Most of the 43 cases of anthracofibrosis were characterized by smooth
luminal narrowing (41 cases, 95%) and peribronchial lymphadenopathy (39 cases,
91%) (Fig. 1A,
1B,
1C,
1D). Sixteen of the 32 cases of
endobronchial TB were characterized by irregular bronchial narrowing (Fig.
2A,
2B,
2C). Peribronchial and
mediastinal lymphadenopathy were more commonly associated with
anthracofibrosis than with endobronchial TB (p < 0.05, Student's
t test).
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Fig. 1A —81-year-old woman with anthracofibrosis who presented with
cough and sputum. Axial CT scan obtained with lung window setting at level of
right main pulmonary artery shows smooth luminal narrowing (arrows)
at segmental bronchi of right upper lobe.
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Fig. 1B —81-year-old woman with anthracofibrosis who presented with
cough and sputum. Contrast-enhanced CT scan at same level as A shows
enlarged nodes around right upper lobe bronchus (black
arrows), in subcarinal region (arrowhead), and around left
upper lobe bronchus (white arrow).
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Fig. 1D —81-year-old woman with anthracofibrosis who presented with
cough and sputum. Bronchoscopic image shows luminal narrowing of right upper
lobe bronchus with focal deposition of black pigmentation (arrows).
Pathologic specimen obtained at bronchoscopic biopsy revealed chronic
inflammation without granuloma.
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Fig. 2A —34-year-old woman with endobronchial tuberculosis who
presented with dyspnea. Sputum acid-fast stain result was positive for
acid-fast bacilli. Axial CT scan obtained at lung window setting shows uneven
contiguous luminal narrowing (black arrow) of left main and
upper lobe bronchi. Multiple small nodules are clustered with linear branching
opacities (white arrows).
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Fig. 2B —34-year-old woman with endobronchial tuberculosis who
presented with dyspnea. Sputum acid-fast stain result was positive for
acid-fast bacilli. Contrast-enhanced CT scan at same level as A shows
focal soft-tissue attenuation around stenotic airway (arrow).
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Fig. 2C —34-year-old woman with endobronchial tuberculosis who
presented with dyspnea. Sputum acid-fast stain result was positive for
acid-fast bacilli. Bronchoscopic image shows diffuse stenosis of left main
bronchus with luminal irregularity. Left main bronchus is hyperemic with
purulent secretions. Pathologic specimen obtained at bronchoscopic biopsy
revealed chronic inflammation and epithelioid granuloma with caseous
necrosis.
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The distribution of bronchostenosis was statistically different in
comparisons of the CT findings for the two groups (p < 0.05,
Student's t test and Pearson's chi-square test). More lobes were
involved in anthracofibrosis than in endobronchial TB (mean, 3.1 vs 1.3 lobes;
p = 0.0001). Bilateral lung involvement was more common in
anthracofibrosis than in endobronchial TB (65% vs 6% of patients, p =
0.0001). The most common location of bronchostenosis in anthracofibrosis was
the right upper lobe (42 [98%] of 43 cases) and in endobronchial TB was the
left upper lobe (22 [69%] of 32 cases). Bronchostenosis in the right upper
lobe, or in any lobe of the right lung, was more common in anthra co fibrosis
than in TB (p < 0.05). Both anthra co fibrosis and TB commonly
involved the left upper lobe, but the difference was not statistically
significant (53% vs 69%, p = 0.236). Only left lung involvement was
absent in anthracofibrosis. In anthracofibrosis, the main bronchus and trachea
were usually unaffected (three of 43 cases, 7%) (Fig.
3A,
3B,
3C,
3D). Endobronchial TB extended
contiguously along the ipsilateral main bronchus and distal trachea (28 [88%]
of 32 cases) (Fig. 4A,
4B,
4C).
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Fig. 3A —82-year-old woman with anthracofibrosis who presented with
dyspnea. Axial CT scans obtained at lung window setting (main bronchus level,
A; right middle lobe bronchus level, B; right inferior pulmonary
vein level, C) show multifocal smooth bronchial narrowing of segmental
bronchi of three lobes of right lung and left upper lobe (straight
arrows, A–C). Both main bronchi are preserved. There is
no contiguity in disease extent. Volume loss of right middle lobe
(curved arrow, C) is evident.
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Fig. 3B —82-year-old woman with anthracofibrosis who presented with
dyspnea. Axial CT scans obtained at lung window setting (main bronchus level,
A; right middle lobe bronchus level, B; right inferior pulmonary
vein level, C) show multifocal smooth bronchial narrowing of segmental
bronchi of three lobes of right lung and left upper lobe (straight
arrows, A–C). Both main bronchi are preserved. There is
no contiguity in disease extent. Volume loss of right middle lobe
(curved arrow, C) is evident.
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Fig. 3C —82-year-old woman with anthracofibrosis who presented with
dyspnea. Axial CT scans obtained at lung window setting (main bronchus level,
A; right middle lobe bronchus level, B; right inferior pulmonary
vein level, C) show multifocal smooth bronchial narrowing of segmental
bronchi of three lobes of right lung and left upper lobe (straight
arrows, A–C). Both main bronchi are preserved. There is
no contiguity in disease extent. Volume loss of right middle lobe
(curved arrow, C) is evident.
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Fig. 3D —82-year-old woman with anthracofibrosis who presented with
dyspnea. Contrast-enhanced CT scan at same level as A shows multiple
enlarged nodes around stenotic bronchi and high-attenuation foci
(arrowheads) in subcarinal region.
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Fig. 4A —56-year-old man with history of endobronchial tuberculosis 10
years in past who presented with dyspnea. Contrast-enhanced CT scan at level
of carina shows smooth luminal narrowing of right main bronchus
(straight arrow). Right upper lobe bronchus is completely
obstructed, resulting in peripheral atelectasis (curved
arrow).
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Fig. 4B —56-year-old man with history of endobronchial tuberculosis 10
years in past who presented with dyspnea. Contrast-enhanced CT scan at level
of aortic arch shows luminal narrowing of distal trachea with evenly thickened
tracheal wall (straight arrow). Collapse of right upper lobe
(curved arrow) is evident.
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Fig. 4C —56-year-old man with history of endobronchial tuberculosis 10
years in past who presented with dyspnea. Bronchoscopic image shows
bronchostenosis of right main bronchus. Opening of right upper lobe bronchus
is obstructed without evidence of mucosal change.
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Discussion
The diagnosis of anthracofibrosis is based on two major bronchoscopic
findings: bronchostenosis and anthracotic pigmentation of overlying mucosa.
This condition occurs commonly among Asian and black persons and is especially
common among older women who present with a chronic cough, sputum, and dyspnea
[1–4].
The pathogenesis of anthracofibrosis remains unknown
[1–4].
Two major hypotheses have been suggested. One is related to wood smoke
inhalation. Many patients with anthracofibrosis are elderly women from rural
regions. They are commonly described as homemakers who have handled firewood
or soft coals in a closed cooking area. Ciliary movement removes most inhaled
anthracotic particles, but residual particles can accumulate at the branching
points of the airway. Anthracotic pigmentation itself does not induce focal
bronchial narrowing because carbon is inert. However, various changes in the
integrity and immunity of the bronchial mucosa can occur in association with
the presence of anthracotic pigmentation, and infection and other forms of air
pollution can induce fibrosis
[2,
7–9].
The other hypothesis on the pathogenesis of anthracofibrosis is the
association of anthracofibrosis with endobronchial TB. There is a high
incidence (41–61%) of coexistence of TB and anthracofibrosis, and the CT
findings are similar for the two conditions. There also is evidence of
development of anthracotic pigmentation during the course of endobronchial TB
[1–4].
Some authors have reported bronchostenosis with anthracofibrosis in patients
responding to anti-TB medication
[3,
10]. Endobronchial TB is
common among young women, and this majority is a common finding in both
endobronchial TB and anthracofibrosis. According to the second hypothesis,
bronchostenosis is thought to be caused by an exaggerated immunologic response
to TB antigens in the lymphatic vessels or contiguous lung, to intraluminal
infection from bacilli originating in upstream cavities, or to extrinsic
compression from proximal intrathoracic lymph nodes
[1–4].
On the basis of this hypothesis, Chung et al.
[1] reported that ant-TB
medication was empirically taken by anthracofibrosis patients without evidence
of active TB, and empiric therapy may be necessary.
Our anthracofibrosis patients were most commonly women older than 70 years.
Coexistent TB was present in 20% of these patients. The rate of coinfection
with TB in our study, however, was lower than that reported in a previous
study [2]. Non tuberculous
pneumonia was present in 30% of our anthracofibrosis patients. The pathologic
specimens from patients with anthracofibrosis who had undergone lobe ctomy and
node dissection exhibited only chronic in flammation and anthracotic
pigmentation without evidence of TB.
The CT findings of anthracofibrosis are bronchostenosis and peribronchial
lymphadenopathy
[1–4].
Bronchostenosis and lympha denopathy, however, are nonspecific findings and
can be manifestations of a number of diseases, both benign and malignant.
Among all of the possible causes of bronchostenosis, carcinoma and TB are two
major diseases that must be differentiated from anthracofibrosis. Bronchogenic
carci noma usually forms endobronchial nodular protrusion and commonly
involves focal areas of a single lobe or segment of bronchus. With these
considerations, malignant broncho stenosis can be easily differentiated from
anthracofibrosis [2].
Differentiation, however, is more difficult when endobronchial TB is
considered. Because of the similarity be tween the radiologic features of endo
bronchial TB and those of anthra cofibrosis, anthracofibrosis can be diagnosed
only with bronchoscopy, not with CT, and a relation between the two diseases
has been suggested
[1–4].
To our knowledge, there has been no report of a comparison of the differences
between anthracofibrosis and endobronchial TB, which are major causes of
benign bronch ostenosis in Korea.
Bronchostenosis was a common CT finding among our patients with
anthracofibrosis and those with TB. Our study showed that bronchostenosis from
anthracofibrosis could be differentiated from bronchostenosis from TB with CT
alone. Bronchostenosis with anthracofibrosis is multifocal and tends to
involve segmental or lobar bronchi in both lungs. The main bronchus and
trachea are preserved, and there is no contiguity in extent of disease. On the
other hand, bronchostenosis with TB involves a single lobar bronchus in a
contiguous spreading pattern along the bronchus. The presence of luminal
narrowing of the ipsi lateral main bronchus and distal trachea is common.
These differences be tween anthra cofibrosis and endobronchial TB may be
evidence against the earlier hypo thesis that TB is a major causative factor
in anthra cofibrosis.
The major limitations of our study were small sample size and selection
bias. Bronchogenic carcinoma, another major cause of bronchostenosis that
should be differentiated from anthracofibrosis, was not included in this
comparison study, and anthracofibrosis patients with a history of pulmonary TB
were included. Thus a few patients with old endobronchial TB might have been
included in the anthracofibrosis group because TB history among
anthracofibrosis patients depended only on medical records and the patient's
memory. In addition, we did not include follow-up data, so we did not know how
many cases of anthracofibrosis would later prove to be endobronchial TB.
Anthracofibrosis can be differentiated from endobronchial TB on CT, so CT
is a useful technique for the diagnosis of anthra cofibrosis before
bronchoscopic evaluation. Endobronchial TB seems not to be a major causative
factor in anthracofibrosis, and empiric anti-TB medication pending confirm
ation of an organism is unnecessary for anthra cofibrosis patients. Further
study is needed to disclose the pathogenesis of anthra cofibrosis.
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Abstract
Introduction
