Myasthenia gravis in ectopic thymoma presenting as pleural masses

Multiple pleural masses were found in a 52-year-old female suggesting malignant mesothelioma or pleural metastasis from other malignancy. Unexpectedly, ectopic thymoma was diagnosed by percutaneous needle biopsy and subsequent myasthenia gravis developed during admission. Although ectopic thymoma in pleura is unusual, it should be considered as one of the possible etiologies causing diffuse pleural masses.