Mediastinal lymph node size in an Asian population.

There is a high incidence of respiratory tuberculosis in the British population of Indian subcontinent (Asian) ethnic origin. Granulomatous diseases can cause long term lymph node enlargement. Separate computed tomography (CT) criteria for normal nodal size could therefore be necessary when staging thoracic malignancy in Asian patients. The objective of this study was to measure mediastinal lymph node size in an Asian population, and to correlate nodal size with previous tuberculosis. Chest CT scans on all Asian patients over a 5 year period were reviewed and those with pulmonary disease, malignancy or grossly distorted anatomy were excluded. The study group consisted of 48 patients (26 male, 22 female) aged 10-75 years (mean 47 years). All nodes were measured and the site of those greater than 7 mm was recorded using the American Thoracic Society (ATS) lymph node map. 81.3% of patients had nodes less than or equal to 7 mm at all ATS stations, 10.4% had nodes of 8-10 mm and 8.3% had nodes greater than 10 mm. All nodes measuring more than 7 mm were in regions 4R, 10R and 7. Fourteen patients had signs of previous tuberculosis, and in this group 50% had nodes greater than 7 mm as compared with 6% in the group with no signs of previous tuberculosis (p < 0.001, X2 test). Despite these differences only four of the 48 patients (8.3%) had nodes greater than 10 mm, which is in keeping with other general population studies. Thus the generally accepted size criteria for mediastinal lymph node enlargement (greater than 10 mm) can reasonably be applied to all Asian patients when staging lymphoma or bronchogenic carcinoma.