CT scanning for the detection of tuberculous mediastinal and hilar lymphadenopathy in children

The diagnosis of primary pulmonary tuberculosis (PTB) in children relies heavily on the radiographic demonstration of mediastinal lymphadenopathy. Plain radiographs may be unreliable and CT is the current ‘gold standard’ for demonstrating this. Only two previous studies have described the CT findings of mediastinal adenopathy exclusively in children.

To determine the prevalence, distribution, characteristics and effect on the bronchial tree of mediastinal lymphadenopathy using modern CT techniques, in children suspected of PTB.

One hundred children (54 boys, 46 girls) with clinically suspected PTB were prospectively recruited from an overnight admission ward if they met the WHO criteria for suspected PTB. CT scans were evaluated by a panel of radiologists with regard to a predetermined set of criteria.

Lymph nodes were present in 92 patients, and nodes greater than 1 cm were present in 46 patients. Enhancement of lymph nodes was present in 67 patients and was almost invariably ‘ghost-like’ ring enhancement. Calcification was present in only 9 patients. The most common location for lymphadenopathy was the subcarinal position (n=90), followed by the hila (n=85; left 74, right 72, bilateral 61), the anterior mediastinum (n=79), the precarinal position (n=64) and the right paratracheal position (n=63). Multiple sites of involvement were present in 88 patients, and a single site for lymphadenopathy (subcarinal) was present in only 4 patients. Bronchial compression was identified in 29 patients. Most commonly, the left main bronchus was involved (n=21), followed by the right main bronchus (n=14) and the bronchus intermedius (n=8), 16 right-sided compressions in total.

Lymphadenopathy was common, but only 46 patients had lymph nodes greater than 1 cm. Enhancement characteristics of tuberculous adenopathy differ from that described previously. Typical enhancement was ‘ghost-like’ rather than discreet ring enhancing with a low-density centre. The site most frequently involved by nodes also differs from previous studies. The subcarinal region should be the site receiving most attention for the identification of lymphadenopathy, as this is most frequently involved and is also the site of the largest lymph-node masses. The presence of lymph-node groups at other recognised sites adds confidence when there is doubt, as multifocal involvement is common. Approximately one-quarter of patients with hilar adenopathy may have bronchial compression in childhood.