CASE 10301 Published on 13.11.2012

Solitary mediastinal pseudo-tumoral mass: an untypical presentation of tuberculosis


Chest imaging

Case Type

Clinical Cases


Eleonora Gaspari 1, Irene Coco1 , Dominique De Vivo1, Alberto Larghi 2, Giovanni Simonetti1.

1. Policlinico Tor Vergata,
Dipartimento di Diagnostica per Immagini,
Imaging Molecolare, Radiologia Interventistica e Terapia Radiante della Fondazione Policlinico Tor Vergata;
Via Regina Bianca 93
95126 Catania, Italy

2.Digestive Endoscopy Unit Università Cattolica del Sacro Cuore,
Largo A.Gemelli 8,
00168, Rome Italy

64 years, male

Area of Interest Mediastinum, Interventional non-vascular ; Imaging Technique Percutaneous, MR, Ultrasound, CT
Clinical History
The patient was referred to our hospital with a 2-week history of lack of appetite, low-grade evening fever, dyspnea and dysphagia for solid food. He reported a persistent cough not accompanied by other manifestations and there was no known contact with tuberculosis patients. The patient's medical history did not include tuberculosis.
Imaging Findings
A chest radiograph revealed slight widening of mediastinum due to a subcarinal expansive lesion.
CT examination demonstrated a solid 7-cm diameter mass in the posterior subcarinal mediastinal compartment, at the carina bifurcation level, with irregular contours and heterogeneous density. The lesion compressed and displaced the medial intrathoracic oesophagus without infiltration. Bilateral pleural effusion was also noted. The imaging findings were suggestive of a benign lesion.
The patient underwent a chest MR imaging study that confirmed the existence of the posterior mediastinal mass, at the medial oesophageal level, which was compressing and relatively stenosing the oesophagus.
US-endoscopic examination, with conventional linear probe, confirmed the presence of subcarinal mass, without further lesions or mediastinal lymphadenopathy and guided the transmural biopsy for histological characterization.
Though mediastinal involvement of tuberculosis is not a rare disease entity, solitary mediastinal pseudotumoral mass with no evidence of tuberculosis elsewhere is unusual. Interaction of the Mycobacterium Tuberculosis with the immune system manifests clinically in two forms, latent infection and active tuberculosis that manifests itself, except in pauci-bacillary forms, and is classified in pulmonary and extrapulmonary forms and primary and secondary forms.
The most common extrapulmonary forms are the pleural and lymph nodes, followed by the genitourinary system, and can have variegated manifestations. However, presenting as an isolated mediastinal mass without parenchymal lesion is unusual [1, 2], yet not so unusual in immunocompromised patients [3].
The presence of mediastinal adenopathy causing necrosis and perforation of the adjacent structures can further cause tracheobronchial-esophageal fistulae. Most studies report variations in size and location, and the most common symptoms are chronic and paroxysmal cough, dysphagia, fever and pneumonia [4].
In solitary tuberculous mediastinal masses there is loss of typical morphological features of lymphadenopathy and enlarged lymphnodes tend to look like pseudotumoral bodies; the last ones were not so easily diagnosed in the past, while nowadays, thanks to the new more refined imaging methods, these lesions can be more precisely identified [5], even if specific radiological patterns do not exist yet.
Chest radiograph was suspicious for a subcarinal expansive lesion. The tuberculin test was non-reactive. Chest CT examination demonstrated a solid 7-cm mass in the posterior subcarinal mediastinal compartment. However, the negative epidemiological history and the absence of tuberculin reaction made diagnosis questionable.
Chest MR study confirmed the existence of the mass.
US-endoscopic examination, with conventional linear probe, showed the subcarinal mass without further lesions or mediastinal lymphadenopathy. However the definite diagnosis requires histological diagnosis [6].
Transmural biopsy through US endoscopy showed diffuse lymphoid tissue with giant cells necrotising and confluent granulomas, compatible with tuberculosis. Acid fast bacilli by Ziehl-Neelsen staining and cultures were positive for the presence of M. tuberculosis DNA by polymerase chain reaction.
The patient responded to antituberculous treatment without complications, drug resistance or side effects with clinical and radiological improvement.
In immunocompetent patients, the extrapulmonary forms only occasionally coexist with active pulmonary TB and though presentation as an isolated pseudo tumoral mediastinal mass is rare, even with a negative tuberculin test and without a history of exposure to adults infected with tuberculosis, it is important to suspect this condition in the appropriate clinical setting.
Differential Diagnosis List
Primary active extra-pulmonary mediastinal tuberculosis.
Malignant lymphoma
Metastatic malignant tumors
Teratomatous neoplasms
Thyroid mass
Granulomatous disease
Bronchogenic cysts
Final Diagnosis
Primary active extra-pulmonary mediastinal tuberculosis.
Case information
DOI: 10.1594/EURORAD/CASE.10301
ISSN: 1563-4086