Noninvasive encapsulated follicular variant of papillary thyroid “cancer” (or not): Time for a name change
A partir de données portant sur 210 patients atteints d'une variante folliculaire encapsulée non invasive ou invasive du carcinome papillaire de la thyroïde, un groupe de travail, constitué de 24 pathologistes de 7 pays, affine les critères diagnostiques et développe une nouvelle nomenclature visant à réduire le surtraitement de tumeurs indolentes
Many subtypes of papillary thyroid cancer (PTC) have been described, of which classic PTC is the most common (70%-80%). The follicular variant of PTC (FVPTC) is the second most common subtype. It has increased in incidence by 4-fold in the last 3 decades, now making up approximately 20% of all thyroid cancers in Europe and North America.
The follicular variant of FVPTC presents several diagnostic and management challenges. Most FVPTCs are encapsulated tumors, which are cytologically difficult to distinguish from benign follicular lesions such as follicular adenoma. Several studies highlight this by demonstrating the considerable interobserver variability involved with the diagnosis of FVPTC.3,4 Multiple studies have shown that encapsulated FVPTCs (EFVPTCs) rarely exhibit lymph node metastases and most behave like a follicular adenoma. Several key retrospective studies have previously demonstrated that the noninvasive EFVPTC (no vascular or capsular invasion) is a highly indolent tumor demonstrating a risk of recurrence of less than 1% in more than 300 previously published cases with extended follow-up, despite the fact that for the majority, treatment consisted of lobectomy only, without radioiodine (RAI) ablation. On a molecular level, oncogenic mutations present in noninvasive EFVPTC are similar to follicular adenoma, with a high rate of RAS mutations and no BRAF mutations.7
JAMA Oncology , éditorial, 2015