Background and clinical significance Squamous cell metaplasia (SCM) is a reversible process in response to chronic injury. While SCM is a standard response to irritation in the proximal bronchi, its occurrence in the distal, non-cartilaginous bronchioles is significantly less common and reflects remarkable epithelial plasticity. In the distal airways, true SCM is rare and typically associated with specific pathologies such as granulomatous inflammation. This case highlights SCM within the bronchiolar epithelium in the setting of pulmonary tuberculosis, where localized cytokine-mediated signaling drives epithelial remodeling beyond its typical anatomical distribution. Case Presentation We report a rare case of pulmonary tuberculosis with bronchiolar SCM manifesting as a growing pulmonary nodule in a 37-year-old female. Due to the lesion’s interval growth and associated fibrous tracking on serial imaging, early-stage lung adenocarcinoma was suspected. Following video-assisted thoracoscopic surgery (VATS) wedge resection, histopathological analysis revealed caseating epithelioid granulomas consistent with active pulmonary tuberculosis. Additionally, the examination identified bronchiolar SCM surrounding the necrotic foci, confirming that the radiological progression was not a malignancy but rather a reactive remodeling process driven by granulomatous inflammation. Conclusions Awareness of this atypical distribution is vital to prevent misdiagnosis. Histopathological evaluation remains the gold standard for differentiating localized granulomatous disease from pulmonary malignancy.
Chivchibashi-Pavlova et al. (Mon,) studied this question.