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Case Report

CT EVALUATION IN DIAGNOSIS OF ENDOBRONCHIAL TUBERCULOSIS

Gupta, Prem Parkash1,; Agarwal, Dipti2; Gupta, K B1; Sood, S2

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doi: 10.4103/0970-2113.44405
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CLINICAL SUMMARY

A 55-year-female housewife, was referred to our Institute for an apparent non-resolving infiltrates in left lower lung field over chest roentgenogram. She had cough with expectoration, intermittent fever and dyspnoea for 5 months. She lost nearly 4 Kg weight and a significant reduction in appetite during this period. She denied any associated haemoptysis or chest pain. Previously, she consulted different private practitioners, was told to have pneumonia and was given various combinations of antibiotics and supportive treatment but with no improvement. There was no history of tuberculosis in past or in family. On clinical examination, she had medium built with a fair nutrition. There was no clubbing or cyanosis. Respiratory movements were decreased on left side. Percussion note was impaired below left scapula. Few crackles were auscultated over left infra-scapular region.

INVESTIGATIONS

Routine hematological and biochemical analyses were within normal limits. Chest roentgenogram PA view [Figure 1] showed radiological lesions suggestive of left lower lobe collapse-consolidation, raised left hemidiaphragm and shifting of cardiac silhouette toward left side. Tuberculin test (1 TU RT 23) produced an induration of 14 mm at 48 hours. Sputum culture and antibiotic susceptibility revealed E. coli sensitive to various second and third generation cephalosporins. Sputum direct smear for the presence of acid-fast bacilli was negative.

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Figure 1:
A zoomed view of chest roentgenogram PA view showing radiological opacity suggestive of left lower lobe collapseconsolidation along with raised left hemidiaphragm and shifting of cardiac silhouette toward left side suggestive of volume loss.

Other investigations included CT thorax and fiberoptic bronchoscopy. An axial CT scan was undertaken for the patient. The axial scans [Figure 2] revealed collapse-consolidation of lower lobe, presence of airbronchogram and a compensatory hyper-inflation of left upper lobe. A volume loss at left side was seen - the mediastinal structures were shifted towards the left side. Longitudinal scans of CT thorax in coronal plane [Figures 3 & 4] illustrated the collapsed left lower lobe, a raised left hemidiaphragm and also endobronchial lesions with stricture formation. Longitudinal scans of CT thorax in saggital plane [Figure 5] demonstrated collapsed lower lobe lying posteriorly with a smooth anterior margin, and the endobronchial lesion. Fiberoptic bronchoscopy demonstrated narrowed lower lobe bronchus due to endobronchial lesion and hypertrophic mucosa along with distorted lumen. The biopsy of the endobronchial lesion (via fiberoptic granulomatous lesion compatible with endobronchial tuberculosis. Bronchial aspirate submitted for direct smear was negative for acid-fast bacilli but culture of specimen for Mycobacterium tuberculosis was positive.

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Figure 2:
CT thorax axial scan enlarged view left side presenting collapse-consolidation of lower lobe, presence of airbronchogram, and shifting of mediastinum towards left side.
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Figure 3:
Longitudinal scan of CT thorax in coronal plane (enlarged view left side) clearly depicted the collapsed left lower lobe, presence of airbronchogram, a raised left hemidiaphragm and also endobronchial lesion showing stricture formation.
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Figure 4:
Longitudinal scan of CT thorax (enlarged view left side) in coronal plane in different window describing endobronchial lesion with stricture formation.
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Figure 5:
Longitudinal scans of CT thorax in saggital plane illustrated collapsed lower lobe displaced posteriorly with a smooth anterior margin due to shifted oblique fi ssure, and the endobronchial lesion.

Diagnosis: Endobronchial tuberculosis with superadded bacterial infection causing collapse consolidation of left lower lobe.

Clinical Course after Diagnosis: She was prescribed anti-tubercular treatment (2HRZE/7HR). Cefpodoxime 200 mg BD was given for initial 15 days along with prednisolone 25 mg OD after breakfast, later for 6 weeks, which was then tapered off over a period of 6 weeks. The patient had significant clinical improvement within a month. She had no significant drug intolerance and successfully completed the 9 months anti-tubercular treatment.

COMMENTS

Endobronchial tuberculosis (EBTB) was first of all described by Morten1 in 1698. It is defined as tuberculous infection of the tracheobronchial tree with a microbial and/or histopathological evidence2. It has been reported in 10-40% of patients with active pulmonary tuberculosis, and more than 90% of these patients have some degree of bronchial stenosis3. EBTB is generally found in the younger age group, a higher incidence in females, with more than half of the cases being seen below the age of 35 years. The duration of symptoms before the initiation of antituberculous chemotherapy is long (on the average 6 months), and they are occasionally treated as bronchial asthma or bronchitis4.

The yield of sputum smear for AFB in these patients is low (16 to 53.3 percent5). Erosion of a calcified nearby lymphnode into bronchus (broncholithiasis) frequently results in collapse or over-inflation. Chest roentgenogram manifestations of tuberculous bronchostenosis include persistent segmental or lobar collapse, lobar hyperinflation, obstructive pneumonia and mucoid impaction6; though a normal chest skiagram does not rule out EBTB and is observed in up to 20% of patients. A volume loss may signify development of bronchial stenosis. Bronchiectasis is another complication of EBTB. Fiberoptic bronchoscopy has been the key to the diagnosis of EBTB, producing a yield in up to 90 percent of patients7. Bronchial biopsy may be positive in 30% to 84% patients8.

CT thorax is a modality that is not generally utilized to its full potential in evaluation of endobronchial tuberculosis. CT examination can determine the site and extent of EBTB and help the localization for bronchoscopic examination9. Chest CT is useful in measuring the length of involved bronchus and degree of stricture in EBTB. In a study, the length of bronchial involvement was observed to be from 10 to 55 mm; bronchial stricture was noticed and the range of narrowing was from total occlusion to near normal, and there was wide variation in bronchial stricture even within same subtype of EBTB10. The volumetric computed tomography of thorax helps in acquiring both multiplanar and three-dimensional (3D) images, thus enabling evaluation of extent of disease involving the airways and the precise diagnosis. Multiplanar and 3D images appear to be useful for comprehensive appreciation of the status of the tracheobronchial tree, primarily for evaluation of focal stenosis of the airways. Such images are especially useful in evaluating the longitudinal extent of airway lesions, thus providing valuable information for preparing a road map for bronchoscopy, for surgical planning, and for follow-up of treatment response. Multiplanar and 3D images are also helpful in demonstrating whether a lesion is peribronchial, submucosal, or endobronchial11.

Characteristic HRCT findings of EBTB are patchy asymmetric centrilobular nodules and branching lines having a unilateral or bilateral distribution12. A ′tree-in-bud′ appearance is suggestive of multiple branching linear structures of comparable caliber initiate from a single stalk - The stalk is contemplated to represent a lesion that affects the last order bronchus within the secondary pulmonary lobule and the bud is considered to represent a lesion that is in the bronchioles and alveolar ducts13. In CT scan, there are foci of ill-defined peribronchiolar nodular densities which are variable in size and may become confluent. Tuberculous mediastinal lymphnodes are typically of low density (necrotic) on chest CT. CT findings include isolated segmental bronchial narrowing with concentric wall thickening (41% to 43%), complete endobronchial obstruction (32%) and extrinsic obstruction by adjacent adenopathy (23% to 50%)13. Sometimes, air trapping present on high resolution CT scan led to focus the examination on proximal airways and to suspect their involvement14. This observation underlines the value of expiratory CT scan in demonstrating proximal stenosis of main bronchi.

The most important goal of treatment in active endobronchial tuberculosis is the eradication of tubercle bacilli. The second most important goal is prevention of bronchial stenosis. Antituberculous chemotherapy is effective in controlling the infection, but does not prevent residual bronchostenosis. Early treatment with steroid therapy is effective in certain groups of EBTB particularly when the interval between symptom onset and treatment with steroid is less than 6 months15. Corticosteroid therapy for prevention of bronchial stenosis in endobronchial tuberculosis remains controversial, but the best results are associated with minimal delay in the intiation of steroid treatment. Balloon dilatation and stent insertion are useful in management of bronchial stenosis, though some workers have reported poor response to stent procedure16. Use of endobronchial stent is considered in few lesions located more proximally and when other dilatational methods have failed13. INH and streptomycin inhalation in addition to standard chemotherapy is also useful in preventing bronchial stenosis in some patients1718. At a late stage, when the patient developed the endobronchial tuberculosis with cicatricial lesion, corrective operation is often needed, sleeve resection being the first choice18.

REFERENCES

1. Hudson EHHeaf ERG. Respiratory tuberculosis: Clinical diagnosis Symposium on Tuberculosis. 1957 London Cassell and Co:321–464
2. Hoheisel G, Chan BK, Chan CH, et al Endobronchial tuberculosis: Diagnostic features and therapeutic outcome Respir Med. 1994;88:593–97
3. Han JK, Im JG, Park JH, et al Bronchial stenosis due to endobronchial tuberculosis : Successful treatment with self- expanding metallic stent Am J Roentgenol. 1992;159:971–72
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11. Lee KS, Yoon JH, Kim TK, Kim JS, Chung MP, Kwon Oj. Evaluation of tracheobronchial disease with helical CT with multiplanar and three-dimensional reconstruction: correlation with bronchoscopy Radiographics. 1997;17(3):555
12. Muller NL, Fraser RS, Colman NC, Pare PD Radiologic Diagnosis of Diseases of the Chest. 2001 Philadelphia W.B. Saunders Co:78–80
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14. Blachere H, Montaudon M, Prisse P, Latrabe V, Portel L, Nguyen L, Laurent F. Air trapping revealing endobronchial tuberculosis J Radiol. 2000;81:887–89
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16. Hoheisel G, Chan BK, Chan CH, et al Endobronchial tuberculosis: Diagnostic features and therapeutic outcome Respir Med. 1994;88:593–97
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18. Rikimaru T. Endobronchial tuberculosis Expert Rev Anti Infect Ther. 2004;2:245–51
Keywords:

Endobronchial tuberculosis; Volumetric CT; Multiplanar CT; Fiberoptic bronchoscopy

© 2006 Lung India | Published by Wolters Kluwer – Medknow