Abstract
BACKGROUND: Fungal infection of the bronchial stump is rare, characterized by insidious clinical manifestations and often misdiagnosed as bacterial infection or tumor recurrence. Most reported cases involve Aspergillus fumigatus, with Aspergillus flavus encountered far less frequently. Importantly, fungal colonization of the bronchial stump by Cryptococcus species has not been previously documented, nor has a mixed infection involving Cryptococcus and other fungi at this site. These rare presentations highlight diagnostic blind spots in postoperative airway management and underscore the need for heightened clinical awareness. CASE DESCRIPTION: Case 1: A 53-year-old man underwent left upper lobectomy for adenocarcinoma four years prior. In 2024, he presented with hoarseness and chest tightness. Positron emission tomography-computed tomography (PET-CT) revealed a metabolically active soft-tissue nodule adjacent to the surgical suture line. Bronchoscopic biopsy combined with metagenomic next-generation sequencing (mNGS) confirmed the diagnosis of bronchial stump aspergillosis (BSA). The patient received posaconazole therapy for 7 months. Case 2: A 77-year-old woman underwent right lower lobectomy for adenocarcinoma six years earlier. In 2025, she developed cough with sputum production. CT demonstrated bilateral pneumonia with focal consolidation/atelectasis and bilateral pleural effusions. Bronchoscopy and mNGS identified a mixed infection with Candida albicans and Cryptococcus neoformans at the bronchial stump. Following treatment with caspofungin and fluconazole, her clinical symptoms improved, and follow-up CT imaging showed resolution of inflammatory changes. CONCLUSIONS: Although fungal infection of the bronchial stump is rare, it warrants early consideration when post-lobectomy patients develop persistent symptoms unresponsive to antibiotics. Early radiological clues-such as unexpected metabolic activity around suture granulomas or localized nodular thickening at the stump-should prompt further evaluation. When conventional cultures remain negative and clinical deterioration continues, early initiation of mNGS can facilitate timely pathogen identification and guide targeted antifungal therapy.