Emergence of pulmonary cryptococcosis in a non-classically immunocompromised patient with type 2 diabetes mellitus and hypertension: a case report

Pulmonary cryptococcosis is an uncommon opportunistic infection that predominantly affects immunocompromised hosts. Its occurrence in non-classically immunocompromised individuals is rare and poses significant diagnostic challenges. A 65-year-old non-classically immunocompromised man with type 2 diabetes mellitus and hypertension presented with chest pain. Initial chest CT revealed consolidation in the left upper lobe. Despite broad-spectrum antibiotic therapy, the symptoms persisted. Bronchoscopy and metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF) definitively identified Cryptococcus neoformans with a high sequence count (999). Despite only occasional headaches, a lumbar puncture was performed and cerebrospinal fluid analysis ruled out meningeal involvement, confirming isolated pulmonary cryptococcosis. The patient was successfully treated with intravenous fluconazole, showing significant clinical and radiological improvement at follow-up. This case suggests that pulmonary cryptococcosis can occur in older, non-classically immunocompromised patients with poorly controlled diabetes and hypertension. It demonstrates the value of metagenomic next-generation sequencing (mNGS) in rapid diagnosis and the necessity of evaluating dissemination. Clinicians should maintain a high index of suspicion for this pathogen in cases of non-resolving pneumonia.