The differential diagnosis for a pulmonary nodule is intriguing in cancer patients. Metastasis might be a preferential diagnosis, and yet possibilities of other medical conditions still exist. Pulmonary tuberculosis should be enlisted in the differential diagnosis for a pulmonary nodule in cancer patients in Korea. This study was aimed at analyzing the incidence and clinical features of pulmonary tuberculosis that were misdiagnosed as pulmonary metastasis during radiologic follow-up in pediatric cancer patients.

We retrospectively studied 422 cancer patients less than 18 years old in the Korea Cancer Center Hospital from January 2001 to June 2007. We collected episodes of lung metastasis of primary tumor and tuberculosis during treatment or follow-up, and analyzed medical records.

There were 5 cases of tuberculosis confirmed after surgery which were initially regarded as cancer. Two patients had respiratory symptoms such as cough and sputum but the other 3 patients did not. One patient had a family history of tuberculosis. Acid-fast M. tuberculosis was found in one case upon tissue specimen analysis. Two cases were Mantoux positive and the sputum examination was negative in all cases. The polymerase chain reaction for tuberculosis on a pathologic specimen was used to differentiate M. tuberculosis from non-tuberculosis mycobacterium (NTM). It was positive in one case. Lung lesions in one case showed a concurrence of tuberculosis along with lung metastasis. One of these patients died after cancer recurrence.

It is necessary to consider the possibility of tuberculosis when a lung mass is newly detected during treatment or follow-up in patients with childhood cancer.