Pulmonary Cryptococcosis (PC) lacks specificity in clinical manifestations and imaging features, making it highly prone to being confused with pulmonary tuberculosis, lung cancer, and other pulmonary infectious diseases. To a relatively high rate of misdiagnosis and missed diagnosis and delays the optimal timing of treatment. This study aims to investigate the clinical, imaging, and pathological characteristics of PC with chronic granulomatous inflammation as the main pathological manifestation, so as to provide a reference for early clinical identification of pulmonary cryptococcosis, rational selection of auxiliary examinations, reduction of unnecessary invasive procedures and antibiotic misuse, and improvement in the diagnosis and treatment of pulmonary fungal diseases.

A total of 20 patients with pathologically confirmed PC and histological manifestations of chronic granulomatous inflammation, admitted to our hospital from January 2023 to June 2025, were enrolled. Their clinical and pathological data were analyzed, and relevant literature was reviewed.

Among the 20 patients, there were 6 males and 14 females. Eight patients were asymptomatic; symptomatic presentations included cough in 8 cases, sputum production in 3, chest pain in 3, fever in 2, dyspnea in 3, and fatigue in 2. A definite history of pigeon exposure was noted in 2 cases. Lesions were located in the right lung in 12 cases (60.00%), left lung in 5 (25.00%), and both lungs in 3 (15.00%); lower lobe involvement was observed in 10 cases (50.00%). Imaging revealed solitary nodules in 11 cases (55.00%) and lesions adjacent to the pleura in 13 cases (65.00%). The lesion diameter ranged from 0.4 to 5.6 cm, with 15 cases (75.00%) having a diameter <3 cm. CT scans predominantly showed highdensity solid nodules, accompanied by groundglass halo sign in 3 cases (15.00%), spiculation sign in 4 cases (20.00%), vacuole sign in 2 cases (10.00%), air bronchogram sign in 2 cases(10.00%), and patchy consolidation in 9 cases (45.00%); cavity and a small amount of pleural effusion were observed in 1 case (5.00%). Histopathologically, all cases exhibited chronic granulomatous inflammation or chronic inflammation with aggregates of multinucleated giant cells and epithelioid cells; among them, 14 cases (70.00%) were of epithelioid granulomatous type, 3 (15.00%) with necrosis, and 3 (15.00%) with organization, without obvious caseous necrosis. PAS and GMS special staining were positive in all 20 cases, clearly revealing cryptococcal organisms and spores. Concurrent PC and lung adenocarcinoma were diagnosed in 2 cases; metagenomic nextgeneration sequencing (mNGS) indicated Cryptococcus infection in 4 cases, sputum culture was positive in 1 case, and bronchoscopy was positive in 1 case.

Pulmonary cryptococcosis presents with insidious clinical manifestations and nonspecific imaging features, and is easily confused with lung cancer and pulmonary tuberculosis. For peripheral subpleural highdensity nodules, especially those with groundglass halo sign and without calcification, PC should be suspected. The combination of HE morphology, fungal special staining (PAS/GMS), and mNGS detection can improve the pathogen detection rate and diagnostic accuracy for PC presenting as chronic granulomatous inflammation.