A case of tuberculosis reactivation suspected of cancer progression during oral tyrosine kinase inhibitor treatment in a patient diagnosed as non-small cell lung cancer

We report a first case of a patient experiencing reactivation of pulmonary tuberculosis (TB) during treatment of oral tyrosine kinase inhibitor (TKI) with non-small cell lung cancer (NSCLC). A 44-year-old male patient visited the hospital with cough. He had been treated with erlotinib (oral TKI) for 8 months after being diagnosed as NSCLC with sensitive epidermal growth factor receptor mutation in our clinic. At initial chest imaging, the patient had fibroatelectatic calcified granuloma in the right upper lobe (RUL) apex as well as 1.9 cm × 2.5 cm sized cancer mass encasing the RUL bronchus. He had not been treated for active pulmonary TB before. He had no known history of contact with active TB patients. During the past treatment period, he had shown overall stable response to erlotinib for 8 months. However, chest computed tomography taken for the fourth response evaluation showed increased number and size of nodules with bronchial luminal narrowing in RUL compared to the last exam, suggesting disease progression. We performed bronchoscopy to re-biopsy the cancer mass. Mucosal biopsy and bronchial washing fluid culture revealed active endobronchial pulmonary TB rather than lung cancer progression. Based on these study results, we started anti-TB medications without changing chemotherapy regimen. After 7 months of treatment for pulmonary TB with erlotinib maintenance, he has been shown successful regression of pulmonary TB with stable chemotherapeutic response. Previously, several reports have described the effect of anti-cancer therapy on the treatment of active TB. However, there has been no case report presenting TB reactivation during oral TKI treatment in NSCLC. Therefore, we suggest that the risk of TB reactivation should be considered in patients with solid organ malignancies even if targeted agents are used. Moreover, misdiagnosis of disease progression must be ruled out.