Impact of parenchymal tuberculosis sequelae on mediastinal lymph node staging in patients with lung cancer

Because tuberculous (TB) involvement of mediastinal lymph nodes (LN) could cause false positive results in nodal staging of lung cancer, we examined the accuracy of nodal staging in lung cancer patients with radiographic sequelae of healed TB. A total of 54 lung cancer patients with radiographic TB sequelae in the lung parenchyma ipsilateral to the resected lung, who had undergone at least ipsilateral 4- and 7-lymph node dissection after both chest computed tomography (CT) and fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT were included for the analysis. The median age of 54 subjects was 66 yr and 48 were males. Calcified nodules and fibrotic changes were the most common forms of healed parenchymal pulmonary TB. Enlarged mediastinal lymph nodes (short diameter > 1 cm) were identified in 21 patients and positive mediastinal lymph nodes were identified using FDG-PET/CT in 19 patients. The overall sensitivity and specificity for mediastinal node metastasis were 60.0% and 69.2% with CT and 46.7% and 69.2% with FDG-PET/CT, respectively. In conclusion, the accuracy of nodal staging using CT or FDG-PET/CT might be low in lung cancer patients with parenchymal TB sequelae, because of inactive TB lymph nodes without viable TB bacilli.