Diffuse large airway lesions caused by bronchial smooth muscle hyperplasia: a case report

Primary pulmonary leiomyoma is a rare entity that originates from the bronchi. It usually draws clinical attention due to symptoms associated with airway obstruction, such as cough, wheezing, hemoptysis, and recurrent pneumonia. On imaging examinations, most cases present as space-occupying lesions in the lungs, and bronchoscopy often reveals neoplasms obstructing the bronchial lumen. The causes of diffuse large airway lesions are complex and rare, commonly including tracheobronchopathia osteochondroplastica, relapsing polychondritis, tracheobronchial amyloidosis, sarcoidosis, granulomatosis with polyangiitis, bronchial tuberculosis, and inflammatory bowel disease. However, cases of diffuse airway wall thickening caused by pulmonary leiomyoma are extremely uncommon. This paper reports a 67-year-old male who underwent chest computed tomography for cough and was found to have diffuse thickening of the tracheal and bilateral main bronchial walls. To further clarify the underlying cause of the airway wall thickening, we performed a comprehensive bronchoscopic examination. Pathological analysis of the biopsy specimen indicated that the thickening was attributed to smooth muscle hyperplasia, and combined with the immunohistochemical findings, a diagnosis of pulmonary leiomyoma was established. This case report supplements the etiological spectrum of diffuse large airway lesions and confirms that bronchoscopic biopsy with pathological examination serves as the gold standard for definitive diagnosis.