Encapsulated papillary thyroid carcinoma: A clinic-pathologic study of 106 cases with emphasis on its morphologic subtypes (histologic growth pattern)
ABSTRACT Encapsulated papillary thyroid carcinoma (EPTC) can have a histologic growth pattern similar to the one seen in classical papillary thyroid carcinoma (PTC) or akin to the follicular variant of PTC (FVPTC). This study aims to assess the behavior of EPTC according to its growth pattern.
All cases of thyroid carcinomas treated at our institution between 1980 and 2000 were reviewed and reclassified according to current histopathologic criteria.
After review by two pathologists, 106 cases were included. Forty-three (41%) of the cases were identified as encapsulated classical PTC (E-CPTC) and 63 (59%) as encapsulated FVPTC (E-FVPTC). E-FVPTC had a higher rate of vascular invasion (16/63; 25%) than E-CPTC (2/43; 5%) (p = 0.007). In contrast, E-CPTC had a higher frequency of capsular invasion (28/43; 65%) than E-FVPTC (24/63, 38%) (p = 0.01). The lymph node metastatic rate was significantly higher in E-CPTC (11/43, 26%) compared to E-FVPTC (2/63, 3%) (p = 0.0014). All 34 noninvasive E-FVPTC lacked evidence of nodal metastases while 4 of 15 (27%) noninvasive E-CPTC presented with nodal disease (p = 0.006). Distant metastasis occurred only in four cases of E-FVPTC at presentation. These four FVPTC had extensive capsular and/or vascular invasion and no nodal disease. None of noninvasive EPTC recurred, including 30 patients treated by lobectomy without radioactive iodine (RAI) therapy (median follow-up: 8.9 years).
E-CPTC resembles classical PTC in its propensity to metastasize to lymph nodes and its vascular/capsular invasive pattern while E-FVPTC behaves more like follicular carcinoma/adenoma group of tumors. Meticulous search for capsular and vascular invasion can reliably predict the metastatic potential of E-FVPTC but not of E-CPTC. The latter can therefore be treated like unencapsulated classical PTC. Noninvasive E-FVPTC could be managed like minimally invasive follicular carcinoma by lobectomy without RAI therapy. Invasive E-FVPTC seem quite indolent if no distant metastases are found at presentation.
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ABSTRACT: Das leitliniengerechte Therapiekonzept des follikulären Schilddrüsenkarzinoms (FTC) bestand bisher in einer totalen Thyreoidektomie mit Lymphknotendissektion und Radiojodtherapie. In Anbetracht des geringen Malignitätspotenzials scheint beim minimal-invasiven follikulären Schilddrüsenkarzinom (MIFTC) ein eingeschränkt radikales Operationsverfahren adäquat. Das MIFTC ist allerdings in der Literatur eine inhomogene Gruppe und unterschiedlich definiert. Daher hat Rosai im Jahr 2005 eine klinisch prognoseorientierte Klassifikation vorgeschlagen, die auf dem Ausmaß von Kapsel- und Gefäßinvasion beruht: das MIFTC mit ausschließlicher Kapselinvasion und mit limitierter Gefäßinvasion (≤3), das gekapselte FTC mit ausgedehnter Gefäßinvasion (>3) und das weit invasive FTC mit grob invasivem Wachstum. Voraussetzung für die Diagnose MIFTC ist die Aufarbeitung des gesamten gekapselten follikulären Knotens oder von mindestens 10Tumorblöcken der Tumorkapsel; der Pathologie kommt somit eine wesentliche therapierelevante Rolle zu. Aufgrund der exzellenten Prognose stellt die Hemithyreoidektomie für das MIFTC mit ausschließlicher Kapselinvasion ein adäquates Operationsverfahren dar, bei limitierter Gefäßinvasion ist es ebenso in Erwägung zu ziehen, unterliegt jedoch noch einer klinischen Prüfung. Es besteht keine Indikation zur Durchführung einer systematischen Lymphadenektomie. Current treatment guidelines for follicular thyroid carcinoma (FTC) recommend total thyroidectomy, lymphadenectomy and radioiodine ablation. Considering the low malignant potential of minimally invasive follicular thyroid carcinoma (MIFTC), a limited radical therapeutic procedure may be adequate. MIFTC is an intensely discussed group of tumors and a review of the literature reveals disagreement among experts concerning the criteria for a distinct definition. Therefore, in 2005 Rosai proposed a clinically more significant classification of FTC based on the extent of capsular and vascular invasion: MIFTC with capsular invasion only, with limited (≤3) vascular invasion, encapsulated FTC with extensive (>3) vascular invasion and broadly invasive FTC with extensive invasive growth. For the diagnosis of MIFTC a complete investigation of the encapsulated follicular lesion should be performed by the pathologist and examination of at least 10 tissue blocks is mandatory. Due to the excellent prognosis hemithyroidectomy constitutes an adequate therapeutic approach in MIFTC with capsular invasion only and may also be considered for MIFTC with limited vascular invasion. There are no indications for systematic lymphadenectomy. SchlüsselwörterMinimal-invasives follikuläres Schilddrüsenkarzinom-Kapselinvasion-Gefäßinvasion-Limitierte Radikalität-Hemithyroidektomie KeywordsMinimally invasive follicular thyroid carcinoma-Capsular invasion-Vascular invasion-Limited radicality-HemithyroidectomyDer Chirurg 07/2010; 81(7):627-635. DOI:10.1007/s00104-009-1884-8 · 0.52 Impact Factor
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ABSTRACT: This article reviews the various morphologic presentations of follicular variant of papillary carcinoma. Most of these can be diagnosed with ease; however, there exists a subgroup which has generated recent controversy in the literature. We present our views based on our experience with the cytologic and histologic diagnosis and clinical follow-up of these tumors, and propose a scheme to assist in their diagnosis and appropriate clinical management.Pathology Case Reviews 11/2009; 14(6):214-218. DOI:10.1097/PCR.0b013e3181c75e9b
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ABSTRACT: To compare the clinicopathologic features of papillary thyroid carcinoma classic variant (PTC-CV) and papillary thyroid carcinoma follicular variant (PTCFV), with a focus on the encapsulated form. In a retrospective search of computerized pathology files for 1996 to 1998, a cohort of 114 cases (58 cases of PTC-CV and 56 cases of PTC-FV) were selected for this study. Clinicopathologic data and long-term follow-up (serum thyroglobulin measurements, radiologic studies, and additional tissue sampling) through the date of compilation of study data were extracted from the medical records. The median patient age at initial diagnosis was 46 years for the PTC-CV group and 45.5 years for the PTC-FV group. Complete tumor encapsulation was seen in 40 PTC-CV cases (69%) and in all PTC-FV cases (100%). A higher rate of tumor capsule invasion (CI), lymphovascular invasion (LVI), extrathyroidal extension, and lymph node metastatic lesions was seen in PTC-CV than in PTC-FV: CI, 26% versus 18%; LVI, 17% versus 4%; extrathyroidal extension, 19% versus 7%; and lymph node metastatic lesions, 68% versus 29%. Clinical, radiologic, or pathologic follow-up data were available in 36 PTC-CV cases (62%) and 34 PTC-FV cases (61%). The median duration of follow-up for the PTC-CV group was 10 years and for the PTC-FV group was 9 years. Tumor recurrence was found in 10 patients with PTC-CV (28%) and 2 with PTC-FV (6%). Distant metastatic lesions occurred in 3 patients with PTC-CV (8%) and 1 patient with PTC-FV (3%) (P = .17); of these, 2 cases of PTC-CV were encapsulated and showed CI, LVI, and lymph node metastatic lesions. Our current study confirms previous reports that both encapsulated PTC-CV and encapsulated PTC-FV are indolent tumors and are associated with very low mortality.Endocrine Practice 05/2010; 16(6):952-9. DOI:10.4158/EP10060.OR · 2.59 Impact Factor