Primary endobronchial tuberculosis (EBTb) is a rare Mycobacterium tuberculosis (M Tb) infection involving the bronchial tree without any radiographic lesions in the lung parenchyme. Early diagnosis and treatment are essential to prevent bronchial stenosis or bronchiectasis.
A 16-month-old boy with a 6-month history of cough and wheezing not responding to albuterol and inhaled corticosteroids (CS) presented with a chest radiograph (CXR) demonstrating hyperaeration of the left lung (Figure 1). Bronchoscopy revealed a polypoid mass obstructing the left main bronchus. He had no known exposure to M Tb and his parents were PPD negative. He had frequent visits to Costa Rica and his PPD recently became positive. He underwent bronchoalveolar lavage (BAL) and gastric aspirates, all negative on smear, culture and PCR for M Tb. Biopsy of the mass on two occasions did not show an acid-fast bacillus (AFB) but showed granulomas without necrosis (Figure 2). CT scan of the chest after resection of the mass showed narrowing of the entire left main stem bronchus with submucosal edema and subcarinal lymphadenopathy without compression of bronchus (Figure 3). He was treated with 4 drugs anti-Tb therapy for 6 months, with oral CS for the first three months under the DOT (directly observed therapy) with an excellent outcome (Figure 4).DISCUSSION: EBTb can cause difficult diagnostic and therapeutic problems. The diagnosis is often missed or delayed. Late diagnosis may contribute to a cicatricial bronchostenosis and bronchiectasis despite an efficacious anti-Tb therapy. EBTb is usually suspected by clinical findings and CXR evidence of bronchial obstruction. Clinical presentation of EBTb in children is often nonspecific. Rare cases may present with stridor, respiratory distress, asthma, or suspicion of foreign body aspiration. The physical findings are related to the associated conditions such as atelectasis of the involved lobe or airway obstruction.Finding the cause of wheezing in an infant can be a diagnostic challenge. It is very common but has diverse etiologies. Poor response to the bronchodilator suggests a fixed lesion. A 2-views CXR is the first step. Unilateral hyperinflation may be secondary to lesions causing either intrinsic or extrinsic airway obstruction. Unilateral hyperaeration is unusual in EBTb, noted only in 1.5% of the cases. Direct examination with a rigid bronchoscope is the diagnostic method of choice, when biopsies taken and the specimen sent for pathology, cytology, and cultures for Tb. Tuberculous granulomas may be devoid of necrosis in the early stages.The pathogenesis of EBTb is not fully understood. Potential mechanisms suggested are a direct extension from the adjacent parenchymal infection (i.e. cavity), implantation of organisms from the infected sputum, a hematogenous dissemination, erosion of a lymph node into the bronchus, and lymphatic drainage from the parenchyma to the bronchus. Our patient probably had Tb infection from an unidentified source. It is not clear why the inhaled AFB was able to establish in bronchus.AFB smear and culture are positive only in 30-40% of children and 70% in infants with pulmonary Tb (gastric washings 47%, BAL 11%, and bronchial biopsy 84%). Recent conversion of PPD was very helpful in establishing diagnosis of M Tb in children. Our patient met the criteria of CDC for culture negative pulmonary Tb.Treatment with 4 drugs regimen (isoniazid, rifampin, pyrazinamide, and ethambutol) is indicated when the source of infection is unknown. Addition of CS has been found to be useful only when used early in the course of the disease.
This case highlights several clinical lessons: 1. all that wheeze are not asthma. 2. the importance of CXR for evaluation of persistent wheezing, 3. consideration of EBTb in differential diagnosis of unilateral hyperaeration.
CDC Criteria for Culture Negative Pulmonary Tuberculosis1. Positive PPD with 5 TU (5 mm or greater induration2. Intitial AFB smears and cultures are negative3. No other diagnosis has been established after appropriate evaluation4. Clinical or radiological response within 2 months of intiation of chemotherapy
R.V. Shah, None.