Pulmonary cryptococcosis often manifests as isolated or multiple nodules, easily mimicking lung cancer clinically and radiologically, which ascribes the poor sensitivity of Cryptococcus culture and rarely positive of Cryptococcal antigen test in the absence of disseminated disease. Therefore, the aim of this study was to develop a predictive scoring system from the perspective of available clinical indicators, to differentiate cryptococcosis from adenocarcinoma in pulmonary nodules, which might be beneficial for the delicacy management of pulmonary nodules.

Nodule is generally defined as a small, approximately spherical in morphology, circumscribed focus of abnormal tissue on computed tomography (CT) and no greater than 3cm in maximum diameter. Pulmonary nodules are not uncommon. A systematic review of CT screening lung cancer trials noted that a lung nodule was detected in up to 51% of study participants. More than 95% of detected nodules are benign and have a wide variety of causes, including infections, granulomatous disease, hamartomas, arteriovenous malformations, round atelectasis, and lymph nodes.

Pulmonary cryptococcosis is caused by Cryptococcus spp., a ubiquitous budding yeast-like basidiomycete that is endemic in many countries. Previously, Pulmonary cryptococcosis was thought to be an important opportunistic invasive mycosis in immunocompromised patients, such as AIDS, immunosuppressor used after organ transplantation, but it is also common in immunocompetent patients. Pulmonary cryptococcosis often manifests as isolated or multiple nodules, easily mimicking lung cancer clinically and radiologically, which ascribes the poor sensitivity of Cryptococcus culture and rarely positive of Cryptococcal antigen test in the absence of disseminated disease.

Therefore, the aim of this multicenter observational study was to develop a predictive scoring system from the perspective of available clinical indicators, to differentiate cryptococcosis from adenocarcinoma in pulmonary nodules, which might be beneficial for the delicacy management of pulmonary nodules.

Inclusion Criteria:

• Patients with pulmonary nodules
• Evidence of pathological diagnosis for cryptococcosis or adenocarcinoma
• Data on high-resolution computed tomography (HRCT)

Exclusion Criteria:

• Pulmonary nodules greater than 3cm in maximum diameter
• Lack of data on HRCT

Patients with pulmonary nodules, no greater than 3cm in maximum diameter, finally diagnosed with cryptococcosis or adenocarcinoma were included in this study.