A case of pulmonary Mycobacterium heckeshornense infection coexisted with lung cancer.

A 71-year-old male was referred to our institution for further examination of chest abnormal shadow. A cavitation in the right apical region, a mass adjacent to the pleura in the right upper lobe, and a nodule in the right middle lobe were observed in a chest computed tomography. The sputum smear and culture of acid-fast bacilli were positive, and Mycobacterium heckeshornense (M. heckeshornense) was identified with the matrix-assisted laser desorption ionization time-of-flight mass spectroscopy. Moreover, computed tomography-guided biopsy of a mass adjacent to the pleura in the right upper lobe yielded the diagnosis of primary lung adenocarcinoma. Taken together, the patient was finally diagnosed as coexistence of pulmonary M. heckeshornense infection and primary lung cancer. An anti-mycobacterial treatment with rifampicin, ethambutol and clarithromycin and a combined chemotherapy were fairly successful for pulmonary M. heckeshornense infection and primary lung adenocarcinoma, respectively. These observations suggest that triple anti-mycobacterial therapy may contribute to good controls of M. heckeshornense infection and that careful selection of anti-cancer drugs against lung cancer might be lead to favorable outcomes even during the course of anti-mycobacterial treatment. To the best of our knowledge, this is the first report of pulmonary M. heckeshornense infection coexisted with lung cancer. J. Med. Invest. 71 : 327-331, August, 2024.