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

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Managing Thyroid Tumors Diagnosed as NIFTP, Endocr Pract. 2017;23(No. 9)

tion; however, there is no guarantee that the entire tumor periphery was submitted for histopatholog- ic evaluation to exclude invasion either into the tumor capsule, surrounding thyroid, or vessels. Thus, NIFTP should be viewed as a newly appre- ciated pathologic diagnosis that should not be applied retrospectively. (b) A benign clinical course after surgery with a low serum thyroglobulin test and a negative neck ultrasound is the most important outcome and ultimately is more important than the pathologic nomenclature. Moving forward, the AACE favors careful education of pathologists and endocri- nologists regarding the precise and prospective diagnosis of NIFTP tumors to allow for unbiased clinical and pathological study of the new catego- ry and its outcomes. (2) “If my tumor is reclassified as NIFTP, do I still need any long-term follow-up with an endocrinologist? “ (a) Since NIFTP cannot be diagnosed prior to surgery, at a minimum, removal of at least half of the thyroid is still required. Although many patients may have had more aggressive surgery and/or treated with radioiodine, these patients were treat- ed according to the best knowledge available at the time of their diagnosis.  (b) Since NIFTP is a new diagnostic entity, at this point what constitutes optimal follow-up is uncer- tain. In the absence of data, we are unable to provide evidence-based recommendations. Until data are available, each case should be considered individually based on risk factors. (3) “I was told I had cancer and now I am told I do not. Who is responsible for my misdiagnosis?” (a) Things change regularly in medicine as our knowledge advances. At the time of the origi- nal treatment, no one (surgeon, endocrinolo- gist, nuclear medicine physician) knew that the follicular variant of PTC diagnosis was in ques- tion. You were treated appropriately according to treatment guidelines at the time. In general, the AACE does not advocate for retrospective review of previously adjudicated EFVPTCs because: (i) Proper reclassification demands retrieval of the tumor block with repeat comprehen- sive sectioning to document the integrity of surrounding tissue and tumor capsule and the absence of papillary structures, lympho- vascular invasion, papillary cancer variants, psammoma bodies and tumor necrosis. (ii) In many cases, the tumor block and appropri- ate slides are no longer available or interpre- table.

(iii) In most cases, the clinical course over the first 5 to 10 years after primary therapy is as powerful a predictor of future tumor behavior as the pathologist’s impression of the recut tumor block. (iv) Most thyroid cancer experts believe that the new NIFTP criteria should optimally be implemented in prospective rather than retro- spective fashion to allow for unbiased clinical and pathological study of the new category and its outcomes. CONCLUSION Based on clinical cohort studies demonstrating favor- able long-term outcomes, the Endocrine Pathology Society Working Group has reclassified a noninvasive subset of follicular variant of papillary cancers (noninvasive EFVPTC) as NIFTP, thereby diminishing the psychologic stigma of the word “cancer” for patients worldwide. It is our hope that the new NIFTP classification will eventually diminish clinical confusion among pathologists, endocri- nologists, and endocrine surgeons and increase the use of diagnostic (and therapeutic) thyroid lobectomy while dimin- ishing thyroid hormone dependency and radioiodine use in affected patients. The purpose of this communication is to relay the clinical implications of the NIFTP thyroid tumor reclassification to academic and community cytologists, pathologists, endocrinologists, and endocrine surgeons across the globe. Although we recognize that long-term prospective NIFTP clinical outcome studies in academic and community settings are needed to validate this change in thyroid cancer diagnosis and treatment, we accept this paradigm shift based on our current level of knowledge. ACKNOWLEDGMENT This manuscript was reviewed and approved by the members of the AACE Thyroid Scientific committee and Endocrine Surgery Scientific Committee. DISCLOSURE The authors have no multiplicity of interest to disclose. REFERENCES 1. Meissner W, Warren S. Tumors of the Thyroid Gland. 2nd Series. Vol Fascicle 4. Washington, DC: Armed Forces Institute of Pathology; 1984. 2. Meissner WA. Follicular carcinoma of the thyroid; frozen section diagnosis. Am J Surg Pathol. 1977;1:171-175. 3. Lindsay S. Carcinoma of the thyroid gland: a clinical and patho- logic study of 239 patients at the University of California Hospital. Springfield, IL: Charles C Thomas; 1960. 4. Chen KTC, Rosai J. Follicular variant of thyroid papillary carci- noma: a clinicopathologic study of six cases. Am J Surg Pathol. 1977;1:123-130.

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