Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features in Asian Practice: Perspectives for Surgical Pathology and Cytopathology

Abstract

The introduction of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was initiated and promoted by pathologists. Recent Asian studies added new knowledge to the existing literature to aid a better understanding of NIFTP. Our original data and the results of a meta-analysis suggest that the initial rate of NIFTP has been overestimated, averaging 9.1% (95% confidence interval [CI] 6.0–12.7%) of all papillary thyroid cancers worldwide. The incidence of NIFTP in the Asian population (1.6%, 95% CI 0.9–2.5%; 7 studies) is significantly lower than that reported in the non-Asian series (13.3%, 95% CI 9.0–18.3%; 18 studies). Such difference could be attributed to various perceptions of histological diagnostic thresholds, different nature of papillary thyroid carcinoma, and different approaches in the management of thyroid nodules. The active surveillance for indeterminate nodules and NIFTP, largely represented in the indeterminate cytologic categories, promoted by Japanese institutions establishes a new paradigm to reduce overtreatment of these patients. The lower prevalence of NIFTP in the Asian series indicates a low impact on the risk of malignancy in cytopathology, as it was demonstrated in our original multi-institutional cohort of thyroid nodules, and may predict a low impact on the performance of commercial molecular tests. Several Korean studies addressed the issue of BRAF mutation in NIFTP, which prompted the current refinement of the diagnostic criteria for NIFTP. Our survey of Asian pathologists found that the term NIFTP has not been universally adopted in the local practice. Endocrine pathologists must promote the new entity through provision of educational activities.

The new 4th edition World Health Organization classification for thyroid tumors, Asian perspectives

“…In our Asian and Australasian experience, the vast majority of borderline tumors are diagnosed in the benign category (FA), and clinically significant cancers are rarely missed using this conservative approach . However, some intrathyroidal tumors are true malignant tumors and have a non‐negligible risk for structural disease recurrence, such as non‐encapsulated 2‐4 cm PTC (5% of recurrence) and BRAF mutated <4 cm PTC (10% of recurrence), but they can be detected preoperatively by applying a multidisciplinary clinical approach by experienced clinicians and pathologists …”

Diagnostic value of HBME‐1, CK19, Galectin 3, and CD56 in the subtypes of follicular variant of papillary thyroid carcinoma

“…This re‐classification provided evidence for limited operation (i.e., lobectomy without lymph node dissection) for NIFTP cases. Furthermore, the Japan Thyroid Association recommended active surveillance without diagnostic surgery for indeterminate thyroid nodules including NIFTP …”

Noninvasive follicular neoplasm with papillary like nuclear features: A comprehensive analysis with a diagnostic algorithm

“…2 new cases in 2012), the prevalence of NIFTP in Asians has not been reported extensively as compared with the western world. 4,5 There are limited studies from Asia and even fewer form India 5-10 and those present have reported a significantly lower prevalence (0%-5%) as compared to western data (15%-25%). 2,[11][12][13][14] Preoperative cytological assessment along with ultra-sonographic evaluation of the thyroid nodule forms the basis of patient management with thyroid nodule, hence, it becomes imperative to identify NIFTP entity at postoperatively to prevent overtreatment and decrease morbidity in these patients.…”

“…Almost 3 years have passed since the introduction of this new entity and experiences from different countries and institutions have been published in an attempt to evaluate whether certain degree of disagreement still persists or whether the new diagnostic criteria are in complete harmony with the diagnosis and management. In spite of Asian continent being a major contributor to worldwide prevalence of thyroid cancer (according to GLOBOCON database; estimated 48% new cases in 2012), the prevalence of NIFTP in Asians has not been reported extensively as compared with the western world . There are limited studies from Asia and even fewer form India and those present have reported a significantly lower prevalence (0%‐5%) as compared to western data (15%‐25%) …”

“…Approximately, 30 studies have been conducted in America, Europe and Asia reporting variable incidence . Bychkov et al, in a meta‐analysis, documented an average worldwide prevalence rate of 9.1%, with a lower rate in Asian studies (1.6%) as compared with non‐Asian countries (13.3%) . This difference could be attributed to various perceptions of histological diagnostic thresholds, different nature of papillary thyroid carcinoma, and different approaches in the management of thyroid nodules.…”