title: Outcome of Large Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features.
abstract: In 2016, encapsulated follicular variant of papillary thyroid carcinoma without invasion was renamed "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) in order to reduce overtreatment of this indolent tumor. However, many endocrinologists remain uneasy about managing large (≥4 cm) NIFTP conservatively without radioactive iodine (RAI) therapy. The objectives of this study are to characterize the clinicopathologic characteristics and outcome of large NIFTP in order to assist therapeutic decision making.
  
  
  
  The pathology databases of four tertiary hospitals were searched for large (≥4 cm) NIFTP. Cases with separate foci of carcinoma were excluded. Seventy-nine cases fulfilled the inclusion criteria. Among them, 56 (71%) had at least two years of clinical follow-up (FU), and 49 (62%) had four or more years of FU. The clinicopathologic characteristics were reviewed and documented by four endocrine pathologists.
  
  
  
  The median size of the NIFTP was 4.5 cm (range 4.0-8.0 cm). The entire capsule was sampled in 50 (63%) tumors, while in the remaining 29 (37%) cases, it was submitted representatively, with a median of 2.1 blocks per centimeter of tumor examined. Large NIFTP had a female preponderance with a male:female ratio of 1:1.8, and presented at a median age of 49 years. There were no lymph node metastases at diagnosis in any of the patients, and none of the patients (n = 25) in whom nodal tissue was available for microscopic examination had positive findings. Twenty-six (33%) underwent thyroid lobectomy alone, and 37 (47%) did not receive RAI ablation. No recurrence was observed in the entire cohort, including all 32 patients with two or more years of FU who did not receive RAI therapy (median FU: 6.7 years). Among patients with four or more years of FU, all 25 individuals without RAI therapy did not recur, with a median FU of 11.2 years. Patients with a larger tumor size tended to receive postoperative RAI ablation (p = 0.001).
  
  
  
  Similar to their small counterparts, large NIFTP appear to have an extremely low risk of recurrence (zero in this cohort), even when treated conservatively without RAI therapy. Surgical treatment alone, including lobectomy, appears to be adequate for large NIFTP.
authors.affiliation: 1 Department of Pathology, Sunnybrook Health Sciences Centre , Toronto, Canada .
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.affiliation: 2 Department of Pathology, Bologna University School of Medicine , Bologna, Italy .
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tallini
authors.affiliation: 3 Department of Pathology, Cornell University , New York, New York.
authors.forename: Theresa
authors.initials: T
authors.lastname: Scognamiglio
authors.affiliation: 4 Department of Surgery, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Benjamin R
authors.initials: BR
authors.lastname: Roman
authors.affiliation: 5 Department of Medicine, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: R Michael
authors.initials: RM
authors.lastname: Tuttle
authors.affiliation: 6 Department of Pathology, Memorial Sloan Kettering Cancer Center , New York, New York.
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Ghossein
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000473:pathology / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000473:pathology / Q000628:therapy*; D000066491:Clinical Decision-Making; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology / Q000628:therapy*; D013965:Thyroidectomy / Q000379:methods*; D016896:Treatment Outcome; D047368:Tumor Burden; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes
keywords: follicular variant; noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP); papillary thyroid carcinoma; radioactive iodine