Transection of the Right Intermediate Bronchus Caused by Rhizopus arrhizus: A Case Report.

BACKGROUND: Pulmonary mucormycosis is a rare, life-threatening fungal infection caused by Mucorales, mainly affecting immunocompromised patients. Angioinvasion is the hallmark of mucormycosis, but bronchial invasion is rarely reported. Indeed, bronchial transection secondary to mucormycosis is extremely rare and underreported. Herein, we report a case of Rhizopus arrhizus-associated pulmonary mucormycosis with intermediate bronchial transection, which was successfully treated with combined antifungal therapy and urgent surgical resection. CASE PRESENTATION: A 25-year-old male with type 2 diabetes mellitus presented with persistent cough, fever, and progressive dyspnea. Lesions on the right lower lobe significantly showed progressed on computer tomography scans after 5 days empirical antibacterial therapy. Subsequently, bronchoscopy was utilized to detect the potential pathogenic bacteria, and then Rhizopus arrhizus was identified by metagenomic next-generation sequencing (m-NGS) using bronchoalveolar lavage fluid (BALF). Despite 2 months of aggressive antifungal therapy (liposomal amphotericin B combined with isavuconazole), the patient's dyspnea worsened, and repeat bronchoscopy subsequently confirmed complete transection of the intermediate bronchus, which had not been detected initially. High-resolution computed tomography (HR-CT) revealed occlusion of the right intermediate pulmonary artery and lower pulmonary vein. The patient underwent right pneumonectomy, and postoperative histopathology confirmed mucormycosis. He recovered uneventfully and completed 8 weeks of isavuconazole maintenance therapy. CONCLUSION: Right intermediate bronchial transection caused by Rhizopus arrhizus is a rare but fatal complication. Early diagnosis via mNGS, combined antifungal therapy, and urgent surgical resection are beneficial for patients with severe pulmonary mucormycosis infection.