Mycobacterial kansasii infection mimicking lung cancer with secondary myelofibrosis

초록

Introduction We report a rare case that lung cancer was strongly suspected but diagnosed with mycobacterial kansasii (M. kansasii) infection on the final repetitive biopsy results with secondary myelofibrosis due to infection. Case Report The 68-year-old women who had symptom of dyspnea was admitted to the hospital. Chest computed tomography (CT) showed right middle lobe (RML) mass and multiple lymph node enlargement. To diagnose, endobronchial ultrasound-guided transbronchial needle aspiration was conducted, with suspected malignancy on subcarinallymph node. However, on biopsy result, the malignancy findings were not seen. Due to pancytopenia on laboratory finding, we conducted bone marrow biopsy and the result showed grade 2 myelofibrosis which cannot rule out cancer related secondary myelofibrosis. On Positron emission tomography (PET)-CT, RML malignancy with mediastinum, both supraclavicular fossa lymph node metastasis findings were strongly suspected, so we re-performed bronchial washing, but only non-tuberculosis mycobacterium (NTM) was identified. Regarding the images cannot rule out malignancy, we further performed the biopsy at the Lt supraclavicular fossa and right middle lung mass but there were only mycobacterium findings with chronic necrotizing granulomatous inflammation without malignancy findings. For NTM treatment, assuming M. avium, we started rifampin, ethambutol, azithromycin and amikacin. However, in the NTM sensitivity test, M.kansasii was identified and we changed from the existing drugs to isoniazid, rifampin, ethambutol. After 6 months of M.kansasii treatment, CT finding improved, and pancytopenia was also resolved. Conclusion Thus, we could rule out malignancy finally and we diagnosed patient as with rare M.kansasii lung infection and secondary myelofibrosis due to infection.