2018-19 Section 7-Neoplastic and Inflammatory Diseases of the Head and Neck eBook

Reprinted by permission of Endocr Pract. 2017; 23(9):1150-1155.

AACE/ACE Disease State Commentary AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS AND AMERICAN COLLEGE OF ENDOCRINOLOGY DISEASE STATE COMMENTARY: MANAGING THYROID TUMORS DIAGNOSED AS NONINVASIVE FOLLICULAR THYROID NEOPLASM WITH PAPILLARY-LIKE NUCLEAR FEATURES Zubair W. Baloch, MD, PhD 1 ; R. Mack Harrell, MD, FACP, FACE, ECNU 2 ; Elise M. Brett, MD, FACE, CNSC, ECNU 3 ; Gregory Randolph, MD, FACS, FACE 4 ; Jeffrey R. Garber, MD, FACP, FACE 5 ; On behalf of AACE Endocrine Surgery Scientific Committee and Thyroid Scientific Committee

Submitted for publication April 27, 2017 Accepted for publication June 8, 2017 From the 1 Hospital of the University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania; 2 Memorial Health Systems, Inc, Memorial Center for Integrative Endocrine Surgery, Hollywood, Florida; 3 Division of Endocrinology, Diabetes and Bone Disease, Icahn School of Medicine at Mount Sinai, New York, New York; 4 Mass Eye and Ear Infirmary/Mass General Hospital, Harvard Medical School, Boston, Massachusetts; 5 Endocrine Division, Harvard Vanguard Medical Associates, Boston, Massachusetts, Division of Endocrinology, Beth Israel Deaconess Medical Center, Boston, Massachusetts. Address correspondence to Dr. Zubair W. Baloch; Hospital of the University of Pennsylvania, Perelman School of Medicine; 6 Founders, Rm 6.043, 3400 Spruce Street, Philadelphia, PA 19104. E-mail: baloch@mail.med.upenn.edu Published as a Rapid Electronic Article in Press at http://www.endocrine practice.org. DOI:10.4158/EP171940.DSCR To purchase reprints of this article, please visit: www.aace.com/reprints. Copyright © 2017 AACE. ABSTRACT This commentary summarizes the history and reclas- sification of noninvasive follicular thyroid neoplasm with papillary-like nuclei (NIFTP). It reviews the salient histo- pathologic features that are based on immunohistochemical and molecular profiles and serve as inclusion and exclusion criteria. The authors also provide their own point of view regarding the practical issues and possible concerns that may be raised by both clinicians and patients based on the diagnosis of NIFTP. (Endocr Pract. 2017;23:1153-1158) Abbreviations: AACE = American Association of Clinical Endocrinologists; EFVPTC = encapsulated FVPTC; FNA = fine-needle aspiration; FVPTC = follicular variant of papillary thyroid carcinoma; NIFTP = nonin- vasive follicular thyroid neoplasm with papillary-like nuclear features; PTC = papillary thyroid carcinoma

EXECUTIVE SUMMARY Historically, the definition of papillary thyroid carci- noma (PTC) versus follicular thyroid carcinoma was predi- cated on the predominant tumor growth pattern. Thus if the tumor was mostly follicular in pattern on low-power microscopic examination, it was classified as “follicu- lar carcinoma” (1,2). Once the importance of nuclear morphology was appreciated in the diagnosis of PTC (3), experts agreed that thyroid epithelial cell tumors should be identified as papillary by nuclear features, whether or not papillary or follicular architecture was present (4). The “follicular variant of papillary thyroid carcinoma” (FVPTC) was described in the mid-1970s as a tumor with a predominantly follicular growth pattern and the nucle- ar cytomorphology of PTC (4). Following this, 2 major subtypes of FVPTC were described: infiltrative and encap- sulated (5,6). Accumulated data suggest that infiltrative FVPTC, which grows in the manner of follicular carci- noma with invasion into either its thick capsule or vessels within the capsule, is more likely to behave aggressively. In contrast, noninvasive encapsulated FVPTC (EFVPTC) has been observed to behave in a benign fashion like follic- ular adenoma (7-10). This variable morphologic and clini- cal course has led to much controversy in the diagnosis and management of noninvasive EFVPTC. Confusion has been amplified by the lack of interobserver agreement on the minimal diagnostic criteria for EFVPTC among endo- crine pathology experts, causing angst among pathologists and clinicians alike (11,12). Recent clinical follow-up and case-control studies have confirmed that noninvasive EFVPTC behaves in a benign fashion and may be over- treated (10,13). Moreover, recent molecular analyses of EFVPTC tumors have suggested that these tumors may have a unique set of genetic mutations and fusions (14-17).

Copyright © 2017 AACE

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