Recommendations for the Reporting of Surgically Resected Thymic Epithelial Tumors

Abstract

Standardized pathologic reporting of epithelial malignancy of the thymus has been difficult for several reasons. First, some may consider the most common neoplasm of thymic epithelium, the thymoma, to be a benign neoplasm and, therefore, excluded from the “cancer” rubric. While the majority of thymomas behave in a benign manner, some clearly exhibit malignant behavior. Given this, we believe thymomas should be considered epithelial neoplasms of at least low malignant potential and should be pathologically assessed as malignant neoplasms. Second, contrasting nomenclature used in several histologic categorization schemes has made uniformity in reporting difficult in the clinical practice setting and in the research arena.^1–4 Finally, pathologic staging of thymic epithelial tumors can be difficult in practice. The commonly used modified Masaoka staging system requires integration of preoperative imaging, intraoperative findings, pathologic gross findings, and pathologic microscopic findings to arrive at an accurate clinical-pathologic stage relevant to patient management.^5,6 Unfortunately, imaging and intraoperative findings are often not readily available to pathologists, which can lead to inaccurate staging, particularly understaging, of these tumors.