Thyroid Gland Tumors 131 Clinical Research 131 Department of Pathology (K. Kakudo), Wakayama Medical University, Wakayama, Japan; Department of Pathology (RK), Yamanashi Medical University, School of Medicine, Yamanashi, Japan; Department of Pathology (AS), Kyorin University, Medical School, Mitaka, Japan; Department of Laboratory Medicine and Pathobiology (SA), University of Toronto, Toronto, Canada; Department of Pathology (RAD), Lifespan Academic Medical Center, Rhode Island Hospital, New York, NY; Department of Laboratory Medicine and Pathology (JAC), Mayo Clinic, Rochester, MN; Division of Pathology (HN), Sendai Municipal Hospital, Sendai, Japan; Division of Diagnostic Pathology (K. Kameyama), Keio University School of Medicine, Tokyo, Japan; and Department of Surgery (HT), Teikyo University School of Medicine, Tokyo, Japan. Address correspondence to Dr. K. Kakudo, Department of Pathology, Wakayama Medical University, Kimiidera 811-1, Wakayama, 641-8509 Japan. E-mail: kakudo-k@ wakayama-med.ac.jp Endocrine Pathology, vol. 13, no. 2, 131–134, Summer 2002 © Copyright 2002 by Humana Press Inc. All rights of any nature whatsoever reserved. 1046–3976/02/13:131–134/ $11.00 Thyroid Gland: International Case Conference Kennichi Kakudo, MD, PHD, Ryohei Katoh, MD, PHD, Atsuhiko Sakamoto, MD, PHD, Sylvia Asa, MD, PHD, Ronald A. DeLellis, MD, PHD, J. Aidan Carney, MD, Hiroshi Naganuma, MD, PHD, Kaori Kameyama, MD, PHD, and Hiroshi Takami, MD, PHD Abstract The cases of five thyroid tumors were presented and discussed at an international case conference held during the 5th Annual Meeting of the Japanese Endocrine Pathology Society. There was significant disagreement among six pathologists who studied the cases. In this article, we present two of the cases, attempt to explain the reason for disagree- ment in their diagnoses, and propose what should be done to obtain better consensus in diagnosis. Key Words: Thyroid neoplasms; diagnostic disagreement; histologic criteria; carcinoma. macroscopic appearance of the lesions and clinical outcome were not provided. Table 1 shows the diagnoses made by the panel. Case 1 A 70-yr-old female presented with soft neck mass, measuring 4 × 3 cm, at the Sendai Municipal Hospital. Fine-needle aspiration cytology indicated a cellular fol- licular tumor. The patient underwent total thyroidectomy because papillary carcinoma was suspected clinically. Microscopically, the lesion was interpreted as an atypical adenoma. The discussion point of this case was whether the tumor was benign or malignant. The case was submitted to the panel because of concern about this uncertainty. Microscopic Findings Two H&E slides were available for evaluation. The thyroid gland contained a single, circumscribed, partly encapsulated follicular tumor, with a predominantly Introduction At the 5th Annual Meeting of the Japa- nese Endocrine Pathology Society held in Tokyo, Japan, in September 2001, the diagnoses in five cases that had been sub- mitted to an international panel of patholo- gists for diagnosis were discussed. There was significant difference of diagnostic opinion among the panel members. In this article, we present the findings in two of the cases, the diagnoses of the panel mem- bers, and the reasons for differing opinions. We also indicate the need for improved morphologic criteria or more rigorous application of established criteria or both in order to improve consistency in patho- logic diagnosis. Methods and Case Summaries Representative hematoxylin and eosin (H&E)-stained sections of cases 1 and 2 were reviewed independently by six patholo- gists. Clinical information and details of