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International Journal of Endocrinology
Volume 2015, Article ID 938305, 6 pages
Research Article

Subclassification of Follicular Neoplasms Recommended by the Japan Thyroid Association Reporting System of Thyroid Cytology

1Department of Pathology, Nara Hospital, Kinki University Faculty of Medicine, Otoda-cho 1248-1, Ikoma, Nara 630-0293, Japan
2Division of Diagnostic Pathology, Keio University School of Medicine, Tokyo 160-8582, Japan
3Department of Pathology, Kuma Hospital, Kobe 650-0011, Japan
4Department of Human Pathology, Yamanashi University School of Medicine, Yamanashi 409-3898, Japan
5Department of Internal Medicine, Kuma Hospital, Kobe 650-0011, Japan

Received 27 November 2014; Revised 17 January 2015; Accepted 18 January 2015

Academic Editor: Mario Maggi

Copyright © 2015 Kennichi Kakudo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background. The Japan Thyroid Association recently published guidelines for clinical practice for the management of thyroid nodules, which include a diagnostic system for reporting thyroid fine needle aspiration cytology. It is characterized by the subclassification of follicular neoplasms, which is different from other internationally accepted reporting systems. Materials and Methods. This study examined observer variability in the subclassification of follicular neoplasms among 4 reviewers using Papanicolaou-stained smear samples from 20 surgically treated patients with indeterminate cytology. Results. The favor malignant subcategory had high predictive value of malignancy (risk of malignancy: 60–75%) and good agreement among the 4 reviewers . Conclusion. These results clearly confirmed that the risk stratification of follicular neoplasms, which was adapted from cytology practice of high-volume thyroid centers in Japan, can provide clinically helpful information to estimate the risk of malignancy and to triage patients for surgery.