An unusual huge thymoma composed of sclerosing thymoma and type AB thymoma: A case report

RATIONALE: Sclerosing thymoma (ST) is quite a rare disease, as denoted in previous literature. Less than 20 cases of ST have been reported to date. However, the combined thymoma, composed of both type AB thymoma and ST, has never been described before. PATIENT CONCERNS: The subject, a 49-year-old woman, came in with the chief complaint of cough for 10 days. DIAGNOSES: Both the contrast-enhanced computed tomography scan and the ultrasonography showed a huge mass located in the right thoracic cavity with inhomogeneous contrast accompanied by the invasion of the pericardium and pleura. Subsequently, computed tomography-guided core-needle biopsy revealed type B2 thymoma, and type AB thymoma could not be excluded. Based on postsurgical histopathology and immunohistochemical finding, this tumor was given the final diagnosis of ST and type AB thymoma. INTERVENTIONS: After 6 months of adjuvant chemotherapy and local radiotherapy, total thymectomy was performed. OUTCOMES: The patient has been duly followed up for 1 year without any tumor recurrence. LESSONS: ST is a very rare mediastinal neoplasm. Moreover, ST in combination with AB thymoma and affecting a large area, is unprecedented. Whether radiotherapy and chemotherapy have a certain effect on ST requires further investigation. In addition, due to the unclear recurrence rate of ST, long-term follow-up evaluation seems necessary.