Thymic epithelial tumors and metastasis to the brain: a case series and systematic review

Thymic epithelial tumors (TETs) rarely metastasize to the brain. Clinico-pathologic features of TET patients with brain metastasis are not well described.

TET patients referred for consultation or screening for clinical trials are included. Imaging to evaluate for brain metastases was performed when clinically indicated or if required for screening. Tumor tissue from brain metastases was obtained for analysis, when available. Clinical characteristics and survival was evaluated and a systematic review of the literature on brain metastases associated with TETs was performed.

Fourteen TET patients with brain metastasis were identified. Median age at TET diagnosis was 53 years (range: 31-71 years). Twelve patients had thymic carcinoma and two patients had World Health Organization B3 thymoma. Median time from TET diagnosis to discovery of brain metastases was 2.5 years (range: 9 months-8.3 years). Eleven patients had extracranial, extrathoracic metastases during presentation with brain metastases. Three patients underwent surgery and radiation therapy, eight patients received radiation therapy alone, and one patient had surgery alone. One patient with thymoma died 11 months after diagnosis of brain metastases and another patient died but with unknown date of diagnosis of brain metastases. Among 12 patients with thymic carcinoma, 11 of whom had a known date of brain metastases diagnosis, the median potential follow-up is 35.8 months, and median overall survival (OS) from diagnosis of brain metastases is 13.1 months.

Although uncommon, patients with advanced thymic carcinoma can develop brain metastases. Appropriate imaging and aggressive treatment should be considered for these patients.