本研究的目的是报告一例以胸腔积液为唯一表现的孤立性胸膜隐球菌病，经胸膜活检证实为胸腺瘤合并重症肌无力患者，长期糖皮质激素和他克莫司治疗后出现不明原因的胸腔积液。对1例不明原因反复胸腔积液患者的右侧胸膜活检组织进行病理学检查。对胸膜组织进行了真菌成分的形态学分析和宏基因组下一代测序（mNGS）。右侧胸膜的活检标本显示有许多被粘液囊包围的酵母样生物，mNGS 检测到了新型隐球菌，其物种为特异性读数（SSRN）为4，证实胸膜隐球菌病的诊断。胸腔积液用两性霉素B和氟康唑消除，1年后复查时仍保持健康状态。以单纯性胸腔积液为表现的隐球菌病极为罕见，但当免疫功能低下患者或恶性肿瘤患者出现反复胸腔积液时，肿瘤，应高度警惕隐球菌病的可能性，必要时建议进行胸膜活检以明确诊断。版权所有 © 2023 贾、刘、涂、王、何、张。

The aim of this study is to report an isolated pleural cryptococcosis with pleural effusion as the only manifestation, confirmed by pleural biopsy in a patient with thymoma combined with myasthenia gravis, who developed pleural effusion of unknown origin after long-term glucocorticoids and tacrolimus therapy.Pathological examination of the right pleural biopsy tissue from a patient with unexplained recurrent pleural effusion was implemented. Morphological analysis of the fungal component and metagenomic next-generation sequencing (mNGS) on the pleural tissue were performed.A biopsy specimen of the right pleura revealed numerous yeast-like organisms surrounded by mucous capsules and Cryptococcus neoformans was detected by mNGS with a species-specific read number (SSRN) of 4, confirming the diagnosis of pleural cryptococcosis. Pleural effusion was eliminated with amphotericin B and fluconazole, and healthy status was maintained at the time of review 1 year later.Cryptococcosis, manifested by simple pleural effusion, is extremely rare, but when repeated pleural effusion occurs in immunocompromised patients or in patients with malignant tumors, the possibility of cryptococcosis should be treated with high vigilance and pleural biopsy is recommended if necessary in order to confirm the diagnosis.Copyright © 2023 Jia, Liu, Tu, Wang, He and Zhang.