Thymoma Metastasis to the Liver: Case Report

Thymoma is a benign tumor located in the anterior mediastinum and grows slowly. Although local recurrence is frequently observed, it may rarely present with unusual metastases. The present case report describes a patient with mediastinal thymoma, developed liver metastasis three years after thymectomy and radiotherapy. A 37-year-old otherwise healthy female patient was diagnosed with mediastinal B2 thymoma when she was admitted to the hospital with a complaint of cough. In pre-operative staging positron emission tomography, there was only a mass in the anterior mediastinum and no distant metastasis. The patient was received adjuvant radiotherapy following thymectomy. At follow-up after 3 years, abdominal pain occured and a mass was detected in the liver. Partial liver resection was performed. The pathology confirmed metastatic type B1 thymoma. There was no invasion of the capsule or serosal layer. Surgical margin was 0.2 cm. Because of the thymus has an immunogenic structure, Microsatellite Instability (MSI) and Programmed death-ligand 1 (PD-L1) expression was investigated in order to benefit from immunotherapy and new agents. There was no demonstration of MisMatch Repair (MMR) protein and PDL1 expression at our patients. No additional treatment was applied. The patient alives and free of disease now. Thymoma is known generally locally invasive disease. In this case, it should be kept in mind that thymomas, do not have metastasis at the primary diagnosis, may metastasize after curative treatment. An abdominal ultrasound or abdominal magnetic resonance imaging control should be performed perhaps once a year in patients with a history of thymoma. PD-L1 or MSI directed therapy can be given to suitable metastatic patients.