Pathologic Reporting of Lymph Node Metastases in Differentiated Thyroid Cancer: a Call to Action for the College of American Pathologists

Lymph nodes in differentiated thyroid cancer have many different histomorphologic features. The current AJCC staging system does not distinguish between different lymph node characteristics and is based entirely on the presence of metastatic disease to upstage pN0 to pN1. However, clinicians involved in the management of thyroid cancer recognize that there is a difference in the clinical significance of finding macroscopic versus microscopic nodes. There appears to be a difference in disease biology that allows lymph nodes to reach different sizes and to manifest disease extension outside the capsule, which has led clinicians, and even clinical practice guidelines, to stratify nodal metastases on the basis of these features. The inherent presumption is that all lymph node metastases in differentiated thyroid cancer do not have the same clinical significance with respect to the risk of recurrence and the risk of death. However, the College of American Pathology (CAP) has not mandated that pathologists include these findings as part of their standard reporting protocol in thyroid cancer. In order to arm clinicians with the tools to design clinical trials and to make important patient management decisions in the presence of lymph node metastases, it is imperative that the CAP adopt a strategy for more detailed reporting that is similar to the protocol currently utilized in breast cancer pathologic reporting.