CQ12. What Is the Intra-Observer Variation in the Pathological Diagnosis of Follicular Carcinoma?
Follicular carcinoma is a malignant tumor originating from the follicular epithelium and forming a follicular structure. Follicular carcinoma is distinguished from follicular adenoma based on at least one of the following pathological findings; capsular invasion, vascular invasion, or metastasis of tumor cells to other organs. The diagnosis of capsular and vascular invasion differs among pathologists (even among thyroid pathologists), leading to the difference in incidence of follicular carcinoma among institutions. Furthermore, it is difficult to distinguish between multinodular goiter and follicular carcinoma (or follicular adenoma), and inter-observer variation is likely to occur. Although papillary carcinoma is generally thought to be easily diagnosed based on typical nuclear findings, in practice there are nodules with intermediate nuclear findings between follicular tumor and papillary carcinoma, causing inter-observer variation on whether they are follicular carcinoma (or follicular adenoma) or a follicular variant of papillary carcinoma. It is known that there is inter-observer variation in the diagnosis of follicular tumor, but there are very few studies quantifying this issue.
KeywordsVascular Invasion Papillary Carcinoma Concordance Rate Follicular Carcinoma Multinodular Goiter