Secondary Aspergillus candidus Infection in a Lung Cancer Patient with a Heavy Smoking History: A Case Report

Background： Aspergillus candidus ( A. candidus ), while an uncommon clinical isolate, represents an emerging cause of severe invasive fungal disease, particularly among individuals with compromised immunity. Patients with hematologic or solid tumor malignancies—especially those with concomitant structural lung damage, such as results from long-term heavy smoking—are at heightened risk. Case presentation： We describe a case of invasive aspergillosis caused by A. candidus in a 66-year-old man with untreated lung cancer. The patient had a 40-year history of heavy smoking, with known chronic bronchitis and emphysema. Bilateral pulmonary nodules had been identified two years prior, for which he had declined intervention. He presented with complaints of cough, productive sputum, and worsening dyspnea. Chest imaging revealed progression of his underlying malignancy, accompanied by inflammatory changes. Bronchoalveolar lavage fluid was obtained and cultured; mycological analysis yielded colonies morphologically consistent with A. candidus , an identification subsequently confirmed through internal transcribed spacer (ITS) sequencing—the current gold standard for fungal speciation. Conclusions： To our knowledge, this represents the first reported case of A. candidus infection in a treatment-naïve lung cancer patient with an extensive smoking history. It underscores the importance of considering this pathogen in heavily smoking-related lung cancer cases and highlights diagnostic and therapeutic challenges in this high-risk population.