*Bronchoscopy Unit, Pulmonology Department
†Pathology Department, Centro Hospitalar de Gaia-Espinho, EPE
‡Pulmonology Department, Unidade Local de Saúde do Nordeste
Disclosure: There is no conflict of interest or other disclosures.
Reprints: Sergio Campainha, MD, Rua Conceição Fernandes s/n, 4432-502 Vila Nova de Gaia, Portugal (e-mail: email@example.com).
Received November 23, 2012
Accepted January 21, 2013
Mediastinal tuberculosis without lung involvement is an uncommon finding in an immunocompetent adult. We report the case of an 80-year-old male smoker who presented with dyspnea and stridor. He was found to have a mass in the middle mediastinum which also involved the anterior wall and 50% lumen if of the lower trachea. Histology and mycobacterial cultures of the lesion led to the diagnosis of mediastinal tuberculosis. Antituberculous treatment led to complete resolution of airway symptoms and reduction in the size of the mediastinal mass.
Mediastinal mass is a relatively common challenge in pulmonary practice. Its assessment and definite diagnosis are crucial because of its diverse etiology and consequently different management. In the investigation of mediastinal mass, tuberculosis (TB) is always a part of differential diagnosis, especially in the endemic areas. Although tuberculous lymphadenitis is frequently found in children and immunocompromised adults; in immunocompetent adults it is rarely encountered without concurrent parenchymal disease; so alternative diagnoses such as malignancy are more frequently considered.1 The diagnosis of tuberculous lymphadenitis without parenchymal involvement can be challenging in an elderly patient. Sputum examination offers a very low diagnostic yield (sensitivity of 0% to 14%).2,3 In the setting of isolated intrathoracic lymphadenopathy, bronchoscopy may be useful to establish a diagnosis of TB if sputum studies are negative.4,5 More recently, endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has also been used in this setting; this technique has been reported to have a diagnostic yield of 79% (sensitivity and specificity 95% and 100%, respectively) in patients with isolated intrathoracic lymphadenopathy and a high clinical suspicion for TB.6,7
We present a case of an extensive mediastinal mass with tracheal invasion which turned out to be TB that was successfully treated with anti-TB therapy.
An 80-year-old rural male, active smoker presented with gradually worsening expiratory stridor and dyspnea of 2-month duration. Associated symptoms included dry cough and progressive weight loss, which he could not quantify.
On physical examination bilateral wheeze and expiratory stridor were evident. Chest radiograph was normal. Chest computed tomography (CT) revealed a soft-tissue mass surrounding the lower trachea and invading its anterior rim, occluding the lumen by 50% (Fig. 1). No parenchymal lesions could be observed. Hilar and subcarinal adenopathy was also present.
Flexible bronchoscopy revealed a mass invading the distal portion of the trachea and its anterior wall and obstructing of 50% of its lumen (Fig. 2). Laser ablation was carried out to restore airway patency. EBUS-TBNA was performed on the mediastinal lesion, and rapid on-site evaluation only revealed well-formed non-necrotizing granulomas. Histologic analysis of the tracheal mass also revealed non-necrotizing granulomas (Fig. 3). Ziehl-Neelson, Giemsa, and Gram stain did not reveal any microorganisms. Nucleic acid amplification test performed on the histology sample was positive for Mycobacterium tuberculosis. Subsequently, M. tuberculosis sensitive to all first-line drugs was identified on cultural examination (direct exam was negative) of tracheal lesion and bronchial lavage.
No signs of malignant cells were found in histology or bronchial lavage.
The patient was started on quadruple drug anti-TB therapy with isoniazid, rifampicin, pyrazinamid, and ethambutol for 2 months and subsequently with isoniazid and rifampicin, with reduction of mediastinal mass and complete healing of the tracheal lesion (Fig. 4).
Tuberculous lymphadenitis is the most frequent form of extrapulmonary TB. It was previously considered a disease of the childhood, however, the peak age of its onset in developed countries has shifted from childhood to ages of 20 to 40 years. Contemporary series report a median age of approximately 40 years in developed countries.2,8,9
An increase in the total incidence of TB and in proportion of miliary, disseminated, and extrapulmonary TB cases including lymphadenitis has been associated with the epidemic of human immunodeficiency virus infection.10
Taking into account of our patient’s age, he had an atypical radiologic presentation; finding of a middle mediastinal mass reflects features of primary TB, an unusual finding in older patients. Apical infiltrates, cavities, and air-fluid levels are the most frequent features in adult patients, reflecting postprimary TB.11,12
The differential diagnosis of a mass of the middle mediastinum includes goiter, thyroid or tracheal tumors, aortopulmonary paraganglioma, bronchogenic cysts, and lymphomas. It may also represent lymphadenopathy as a result of fungal infection, malignancy, and idiopathic etiologies as sarcoidosis.13 Thymic masses and pericardial cysts have also been reported although it generally occurs in the anterior mediastinum.14
Given the age of our patient, the clinical presentation and the endoscopic features, the most probable diagnosis was primary or metastatic malignancy with invasion of the anterior wall of the trachea. As the patient had severe expiratory stridor, laser ablation was performed with clinical improvement. The presence of non-necrotizing granulomas on histology and a positive nucleic acid amplification test and culture for M. tuberculosis in the histology sample and bronchial lavage made a definite diagnosis of mediastinal TB with tracheal involvement.
Our patient underwent EBUS-TBNA of the mediastinal mass, and cytologic examination had shown non-necrotizing granulomas, supporting the diagnosis of mediastinal TB. Nevertheless conventional TBNA is still a helpful tool in the diagnosis of tuberculous lymphadenopathy. In endemic areas it has been reported to have a diagnostic yield of 85% and is much more cost effective.15
The trachea can be involved by TB because of spread along the peribronchial lymphatic channels or direct tracheal spread by infected sputum. It can also occur by local extension from adjacent mediastinal tuberculous lymphadenitis as in our case.16,17
Patients with central airway lesions from TB can be classified into 2 groups: (1) an active disease group, in which hyperplastic changes and inflammatory edema lead to obstruction; and (2) fibrotic disease group in which stenosis occurs by fibrosis and tuberculomas are usually absent in the bronchial wall. CT in active airway disease shows irregular luminal narrowing with wall thickening, contrast enhancement, and enlarged adjacent mediastinal lymph nodes. In contrast, in fibrotic disease, smooth narrowing of the tracheal lumen with minimal wall thickening is typically seen.18
In the active form of tracheal TB anti-TB therapy is the treatment of choice but, like our patient, some cases with central airway obstruction may need therapeutic bronchoscopy to restore the patency. Stenosis is a fibrotic process and is resistant to medical treatment, and bronchoscopic or surgical intervention is usually needed to restore the luminal patency, depending on its extent and severity. Helical CT is useful in the evaluation before surgical resection, bronchoscopic dilation, or insertion of a stent.19
In our patient regression of the mediastinal mass and healing of the endotracheal lesion were observed after 9 months of anti-TB therapy. As cases of TB and concurrent malignancy have been reported in literature, close follow-up of clinical, radiologic, and endobronchial response to anti-TB therapy should be performed.
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