Abstract
BackgroundThe follicular variant of papillary thyroid cancer (FVPTC), especially the encapsulated non-invasive subtype, is a controversial entity. Recent study suggested using ‘non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)’ for these indolent carcinomas. We evaluated the impact of reclassification from non-invasive encapsulated FVPTCs (EFVPTCs) to NIFTPs in the diagnosis of thyroid nodules with architectural atypia.MethodsWe reviewed 1301 thyroid nodules with architectural atypia in core needle biopsy (CNB) specimens obtained from March 2012 to February 2013. Nodules were classified into atypia of undetermined significance with architectural atypia (AUS-A, 984, 76%) or follicular neoplasm/suspicious for a follicular neoplasm (FN/SFN, 317, 24%). Among them, diagnostic surgery was performed in 384 nodules (30%).ResultsIn total, 160 nodules (42%) presented final malignant diagnoses including 39 non-invasive encapsulated FVPTCs (10%). The malignancy rate was estimated to be 7–35% in AUS-A nodules and 28–49% in FN/SFN nodules. After reclassification, the malignancy rate was much decreased and estimated to be 5–24% in AUS-A nodules, and 23–39% in FN/SFN nodules. Thyroid nodules with final malignant diagnoses were significantly more likely to have a FN/SFN CNB diagnosis, malignant US features and concomitant nuclear atypia in CNB specimens. However, these factors could not differentiate NIFTPs from other malignancies.ConclusionsAfter reclassification of non-invasive EFVPTCs to NIFTPs, the malignancy rate of thyroid nodules with architectural atypia in CNB specimens was decreased. However, there were no preoperative factors differentiating other malignancies from NIFTPs. The presence of malignant US features or concomitant nuclear atypia might help clinicians deciding diagnostic surgery but, these features also might indicate NIFTPs.
Highlights
The follicular variant of papillary thyroid cancer (FVPTC) is a one common subtype of thyroid cancer
We reviewed 1301 thyroid nodules with architectural atypia in core needle biopsy (CNB) specimens obtained from March 2012 to February 2013
Because of the clinically indolent nature of non-invasive encapsulated FVPTCs (EFVPTCs), there was a suggestion that these tumors should no longer be termed as carcinomas, but be diagnosed using an alternative term, a non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) [1,2,3]
Summary
The follicular variant of papillary thyroid cancer (FVPTC) is a one common subtype of thyroid cancer. Because of the clinically indolent nature of non-invasive encapsulated FVPTCs (EFVPTCs), there was a suggestion that these tumors should no longer be termed as carcinomas, but be diagnosed using an alternative term, a non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) [1,2,3]. We evaluated the final pathologic diagnoses of thyroid nodules with indeterminate results, especially with architectural atypia, in CNB specimens. The follicular variant of papillary thyroid cancer (FVPTC), especially the encapsulated noninvasive subtype, is a controversial entity. Recent study suggested using ‘non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)’ for these indolent carcinomas. We evaluated the impact of reclassification from non-invasive encapsulated FVPTCs (EFVPTCs) to NIFTPs in the diagnosis of thyroid nodules with architectural atypia
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