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 Table of Contents  
Year : 2021  |  Volume : 10  |  Issue : 1  |  Page : 89-92

Central versus peripheral lesion on chest X-Ray: A case series of 31 endobronchial tuberculosis patients with negative sputum smears

1 Department of Internal Medicine, University of Medicine and Pharmacy; Ngoc Minh Clinic, Ho Chi Minh City, Vietnam
2 Department of Internal Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Vietnam

Date of Submission24-Nov-2020
Date of Acceptance13-Jan-2021
Date of Web Publication28-Feb-2021

Correspondence Address:
Vu Le-Thuong
Department of Internal Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, 217, Hong Bang, Ward 11, District 5
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijmy.ijmy_216_20

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Background: Clinical characteristics of endobronchial tuberculosis (EBTB) patients whose sputum smears were negative have not been elucidated yet. Method: EBTB patients with negative sputum smears were documented retrospectively at the outpatient pulmonary clinic from late 2015 to early 2019. Results: We described the characteristics of 31 EBTB patients with negative sputum smears. The median age was 36 years (range 18–81 years). The male-to-female ratio is 1:1.58. The “peripheral” lesion group included 16 cases with opacity/consolidation, 2 cases with atelectasis, 1 case with cavitary lesion, and 1 case with pleural effusion. The “central” lesion group included four cases with normal chest X-ray and seven cases with only unilateral hilar enlargement. EBTB patients with “central” lesion were more common the presence of cough, the positive rate of bronchial lavage acid-fast bacilli smear, and the rate of misdiagnosis as pharyngitis, bronchitis, or asthma than that with “peripheral” lesion. Conclusions: EBTB with negative sputum smears was found in adult patients at any age and predominant in females. The diagnosis of EBTB with “central” lesion was more difficult than that with “peripheral” lesion. The location of the lesion could play a role in inducing cough among EBTB patients.

Keywords: Bronchoscopy, chest X-ray, endobronchial tuberculosis, sputum smear

How to cite this article:
Nguyen-Ho L, Tran-Van N, Le-Thuong V. Central versus peripheral lesion on chest X-Ray: A case series of 31 endobronchial tuberculosis patients with negative sputum smears. Int J Mycobacteriol 2021;10:89-92

How to cite this URL:
Nguyen-Ho L, Tran-Van N, Le-Thuong V. Central versus peripheral lesion on chest X-Ray: A case series of 31 endobronchial tuberculosis patients with negative sputum smears. Int J Mycobacteriol [serial online] 2021 [cited 2022 Jul 4];10:89-92. Available from: https://www.ijmyco.org/text.asp?2021/10/1/89/310508

  Introduction Top

Endobronchial tuberculosis (EBTB) is a distinct pattern of pulmonary tuberculosis (PTB) in which the tuberculous infection of the tracheobronchial tree is determined by the microbial and/or histopathological evidence.[1],[2] EBTB was first described in 1698 by Richard Morton, an English physician. This condition could affect any part of the tracheobronchial tree and any layer of the airway wall. Although pathogenesis remains unclear, one of the following mechanisms could be considered: (1) Direct transmission from adjacent parenchymal lesion, (2) implantation from infected sputum, (3) hematogenous spread, (4) erosion of peribronchial lymphadenitis into bronchial lumen, or (5) lymphatic spread.[1],[2] Chung and Lee classified the bronchoscopic appearance of EBTB into seven subtypes, as follows: (A) actively caseating necrosis, (B) edematous hyperemic, (C) fibrostenotic, (D) tumorous, (E) granular, (F) ulcerative, and (G) unspecific bronchitis.[3]

The diagnosis and management of EBTB are challenges for physicians.[4] Clinical manifestation of EBTB is usually atypical. The positive rate of acid-fast bacilli (AFB) sputum smears is low.[2] There is no recommendation of routine performance of bronchoscopy in suspected PTB patients with negative sputum smears, especially in countries with resource limitation. A normal chest X-ray (CXR) could appear in 10%–20% of EBTB patients,[5] or only hilar abnormality could occur on CXR.[6] All aforementioned features contribute to delays in EBTB diagnosis and misdiagnose as other respiratory diseases. Although PTB is a curable disease, the minority of EBTB patients might develop severe sequela of tracheobronchial stenosis, which reduces quality of life significantly.[2] Therefore, early diagnosis and treatment are essential in dealing with EBTB. With this report, we described the characteristics of 31 EBTB patients with negative sputum smears. We hypothesized that there were distinguishing features in EBTB patients with normal CXR or only hilar abnormality, referred to as the “central” lesion group.

  Methods Top

From late 2015 to early 2019, all adult patients with smear negative PTB who undertaken a bronchoscopy were evaluated retrospectively at the outpatient pulmonary clinic, Ho Chi Minh city, Vietnam. The diagnostic criteria of EBTB in our case series were as follows: (1) bronchoscopic features of endobronchial lesion consistent with EBTB and (2) evidence of tuberculous infection, including the positive bronchial lavage resulting from mycobacteria growth indicator tube (MGIT) culture for Mycobacterium tuberculosis, and/or a histopathological result for lesion biopsy suitable for tuberculous granuloma. We enrolled consecutively EBTB patients with negative sputum smears. We excluded participants with a past history of PTB or tracheobronchial stenosis, relating to airway burning, chemical aspiration, or trauma.

Two pulmonologists with more than 15 years of experience evaluated lesions on CXR and bronchoscopy independently. If there was any difference in result, they would discuss for a consensus.

All 31 participants gave their informed consents for inclusion. This case series was conducted in accordance with the declaration of Helsinki and was approved by the committee of the outpatient pulmonary clinic.

  Results Top

There were 122 cases of smear negative PTB undertaken diagnostic bronchoscopy. The rate of EBTB among smear negative PTB was 25.4% (31 participants). 8 out of 31 EBTB patients were >60 years of age. Demographic and clinical characteristics of EBTB participants are shown in [Table 1].
Table 1: Demographic and clinical characteristics of 31 endobronchial tuberculosis participants

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The majority of participants (77.4%) firstly sought treatment from other private clinics and was misdiagnosed with pharyngitis (6 cases), bronchitis (4 cases), pneumonia (10 cases), lung tumor (1 case), or asthma (3 cases). CXR in EBTB patients showed 51.6% (16 cases) opacity/consolidation, 6.5% (2 cases) atelectasis, 22.6% (7 cases) unilateral hilar enlargement, 1 case of cavitary lesion, 1 case with pleural effusion, and 12.9% (4 cases) were normal. Bronchoscopic features of endobronchial lesion were as follows: 45.2% (14 cases) with actively caseating necrosis, 25.8% (8 cases) were fibrostenotic, 12.9% (4 cases) were tumorous, 12.9% (4 cases) were edematous hyperemia, and 1 case was unspecific bronchitis.

We divided the EBTB participants into two groups according to the location of abnormality on CXR. The “central” lesion group included patients presenting normal CXR or only abnormal hilar zone. [Figure 1] illustrates an EBTB patient with “central” lesion. The “peripheral” lesion group included patients presenting opacity/consolidation, cavitary lesion, atelectasis, or pleural effusion. Characteristics of EBTB patients with “central” lesion were compared to those with “peripheral” lesion in [Table 2]. Initial misdiagnosis as respiratory diseases with no lesion observed on CXR (pharyngitis, bronchitis, or asthma) was more common in the “central” lesion group than the “peripheral” lesion group. EBTB patients with “central” lesion were the presence of cough and positive AFB smear of bronchial washing lavage more frequent.
Figure 1: Radiologic abnormality of an endobronchial tuberculosis patient with “central” lesion. (a) Chest radiograph presented the left hilar abnormality. (b) Chest computed tomography scan revealed tumor mass in the left main bronchus (red arrow)

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Table 2: Characteristics of “central” versus “peripheral” endobronchial tuberculosis group

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Bronchial lavage for the detection of M. tuberculosis was positive in six smear cases (21.4%), in 22 cases with polymerase chain reaction (84.6%) and in 27 cases with MGIT culture (87.1%). Bronchoscopic biopsy showed six cases with histopathological evidence of tuberculous granuloma.

  Discussion Top

Previously published studies revealed that EBTB was common in young patients and predominant in females.[3],[7],[8] Kim et al. recorded that EBTB could develop in elderly patients due to tuberculous reactivation following decrease in immunity status through aging processes or reinfection by exogenous M. tuberculosis.[9] Our case series also showed similar results with a median age of 36 years, ranging from 18 to 81 years old, indicating that EBTB could occur in adult patients at any age. The male-to-female ratio was 1:1.58, although in total tuberculosis, males were predominant in the Vietnam Tuberculosis profile 2018.[10]

EBTB patients present a diversity of clinical symptoms which are common in other respiratory diseases.[2] This increases difficulty in the diagnosis of EBTB. In our case series, cough was the most common symptom of EBTB patients (64.5%). The presence of cough was higher in the “central” lesion group than in the “peripheral” lesion group (90.9% vs. 55.0%). Endobronchial tuberculous inflammation was suggested as an etiology of prolonged cough,[11] but the true mechanism of cough in EBTB patients could be more complex. A few patients showed no symptoms when their condition was detected incidentally in the routine examination.[2],[5] Our case series also had two asymptomatic patients belonging to the “peripheral” lesion group. Therefore, the location of lesion could play a role in inducing cough among EBTB patients.

The diagnosis of EBTB will become more difficult when the CXR only reveals obscure findings,[12] or even look normal; the same as in the “central” lesion group. Consequently, misdiagnosis of EBTB as bronchial asthma was reported.[4],[13] Our case series showed that the “central” lesion group had the higher rate of initial misdiagnosis as respiratory conditions with no lesion observed on the CXR (asthma, pharyngitis, and bronchitis). On the other hand, EBTB patients with “central” lesion presented cough more frequently than that with “peripheral” lesion. This could be an important finding to suspect EBTB in the “central” lesion group. In the literature, the characteristics of “barking” cough and the high prevalence of PTB need to be noticed, suggesting EBTB in patients with prolonged cough.[14],[15] Although the rate of smear-positive in previous publications was low,[1],[2] sputum smears for AFB should be noticed in patients suspecting EBTB with “central” lesion because the rate of bronchial lavage smear-positive was higher in this group than the “peripheral” lesion group. Besides, meticulous interpretation of CXR was recommended to avoid omission of diagnostic clues.[6],[16] A chest computed tomography scan may be more useful in detecting abnormalities than CXR, especially in endobronchial masses and enlarged mediastinal or hilar lymph nodes.[11],[17]

A hypothesis was suggested that the development of EBTB could be associated with the high load of tubercle bacilli dispersed into the bronchial lumen in patients with advanced PTB.[18] Nevertheless, the majority of EBTB studies revealed that the positive rate of sputum AFB smear was low.[1],[2] This was explained by the entrapment of sputum relating to endobronchial lesions.[5] Moreover, Jung et al., in their prospective study, showed that no relationship between advanced PTB and the coexistence of EBTB exists.[19] The positive AFB smear and positive M. tuberculosis culture for bronchial lavage in the study of Sahin and Yıldız were 25.0% and 62.5%, respectively.[8] In our case series, they were 21.4% and 87.1%. This implies that a low load of tubercle bacilli might still exist in the pathogenesis of EBTB.

Bronchoscopy has an important role in the diagnosis of EBTB. The median time from the initial visit to defined diagnosis in our case series was 3 weeks (range 0–22 weeks). It is important that bronchoscopy should be performed early, to detect EBTB and make a comprehensive prognosis for suspected PTB patients with negative sputum smears, because the sequela of severe tracheobronchial stenosis could develop in the natural progression of the disease even though the anti-tuberculous treatment had been complied strictly.[1] Moreover, X-pert MTB/RIF assay or MTBDRplus line probe assay performance for bronchial lavage should be considered to detect microbial evidence of EBTB more rapidly and accurately.[20]

  Conclusions Top

EBTB could occur in adult patients at any age and predominantly in females. Early bronchoscopy should be considered in suspected PTB patients with negative sputum smears. Diagnosis of EBTB with “central” lesion was more difficult than that with “peripheral” lesion. The location of lesion could play a role in inducing cough among EBTB patients. However, the small sample size is a significant limitation to this report. Further research with a larger sample size is required.

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Conflicts of interest

There are no conflicts of interest.

  References Top

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World Health Organization. Tuberculosis. Tuberculosis Country Profiles/Vietnam. Available from: https://extranet.who.int/sree/Reports?op=Replet&name=/WHO_HQ_Reports/G2/PROD/EXT/TBCountryProfile&ISO2=VN&outtype=html. [Last Accessed on 2019 Sep 23].  Back to cited text no. 10
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