Thymic Mucoepidermoid Carcinoma: A Systematic Review and Meta-analysis.

Thymic mucoepidermoid carcinoma is a rare tumor that remains poorly characterized and a diagnostic challenge. The aim of this review is to characterize this tumor in a larger cohort of patients using all the available cases in the literature. We systematically searched the PubMed and Scopus database for primary thymic mucoepidermoid carcinoma. A total of 24 studies were included in the final analysis. A total of 41 patients were identified; 23 (56.1%) were male and 18 (43.9%) were female. Mean age was 49.8±21.3 years. Mean tumor size was 7.6±3.5 cm. Twenty (66.7%) were low grade and 8 (26.7%) were high grade. In total, 20 (55.6%) patients were treated with surgery alone. Nodal dissection was performed in 4 cases only. Two patients had MAML2 gene rearrangement and 2 were negative. Follow-up time varied from 2 to 93 months. A total of 13 (44.8%) patients died of disease with a median survival of 12 months. There seems to be a bimodal age distribution with peaks between second and third decades of life, and between sixth and eight decades. Lymph node sampling is frequently not performed; however, we recommend performing it, as it may lead to more accurate staging. There is limited data regarding the utility of MAML2 gene rearrangement in the thymic location. Histologic grade and tumor stage/resectability are the main prognostic factors.