CASE REPORT article
Front. Med.
Sec. Pulmonary Medicine
Mycobacterium Avium Complex (MAC) Lung Infection Mimics Lung Cancer Nodules But Improves After Antibiotic Therapy: A Case Series
Derek Jacobs
John Greene
Lary A Robinson
Moffitt Cancer Center, Tampa, United States
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Abstract
ABSTRACT BACKGROUND Infection with non-tuberculous mycobacterium species commonly can present with lung nodules mimicking lung cancer on routine chest imaging leading to unnecessary invasive procedures. CASE SERIES The authors report three representative cases presenting with minimal or no symptoms where an incidental probable Mycobacterium avium-complex (MAC) infection was discovered mandating evaluation for a potential malignancy. After suspecting that the nodules were likely infectious, the patients were empirically treated with azithromycin alone or in combination with other antibiotics, resulting in an improved the appearance of these nodules on radiographic imaging in size, density, or both, documenting an infectious etiology, thereby preventing more invasive studies and/or surgery. CONCLUSIONS These cases present typical examples of an increasingly common, prevalent infection that can be mistaken for lung cancer, particularly in endemic areas such as the Southeast U.S. Infectious causes are capable of mimicking lung cancer, especially nontuberculous mycobacterium. An empiric, diagnostic 3-month course of azithromycin for suspected MAC lung infection resulting in a significant nodule size reduction verifies that it is infectious and not malignant, thereby preventing invasive, potentially morbid and expensive invasive evaluations including unnecessary surgery.
Summary
Keywords
case report, lung cancer, Lung nodules, Macrolide antibiotics, Mycobacterium avium Complex
Received
08 October 2025
Accepted
06 February 2026
Copyright
© 2026 Jacobs, Greene and Robinson. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Lary A Robinson
Disclaimer
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