Encapsulated papillary thyroid carcinoma: a clinico-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: Background There are three subtypes of follicular variant papillary thyroid carcinoma (fvPTC): completely encapsulated, well circumscribed, and infiltrative. While infiltrative tumors are more aggressive than completely encapsulated, controversy exists regarding management of fvPTC subtypes. We compared the clinicopathologic features of fvPTC subtypes to those of classic PTC (cPTC) to help guide fvPTC management, using cPTC as a reference. Methods A retrospective review was performed on 316 patients with PTC treated at a single institution from 2004 to 2011. There were 197 cPTC and 119 fvPTC tumors, including completely encapsulated (n = 46), well circumscribed (n = 46), and infiltrative (n = 27). Clinicopathologic data were compared between groups. Results fvPTC patients had larger tumors than cPTC patients (1.6 cm vs. 1.2 cm, p = 0.001), but age, sex, and family history did not differ. Thirty-one percent of cPTC tumors had extrathyroidal extension compared to 0 % of completely encapsulated, 0 % of well-circumscribed, and 52 % of infiltrative fvPTC tumors (p p Conclusions Like cPTC tumors, infiltrative fvPTC tumors have aggressive clinicopathologic features and thus should be treated similarly. Conversely, completely encapsulated and well-circumscribed tumors have less aggressive features compared to cPTC and are more self-limiting; however, well-circumscribed tumors still have a notable incidence of lymph node metastasis. Clinicians should consider this variability in their management algorithm for fvPTC.Annals of Surgical Oncology 10/2014; 22(4). DOI:10.1245/s10434-014-4126-3 · 3.94 Impact Factor
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ABSTRACT: Papillary carcinoma is the most common thyroid malignancy. As the cytological diagnosis of papillary carcinoma is not difficult in patients with the usual type of lesion, fine-needle aspiration (FNA) cytology is an effective method for preoperative evaluation. However, this modality is often ineffective in identifying the follicular variant of papillary thyroid carcinoma (FVPTC) due to its similarity to other follicular lesions and the incompleteness of typical nuclear features. Therefore, we investigated the expression of immunocytochemical markers of papillary carcinoma in cytological specimens of FVPTC and evaluated their utilities. The immunoreactivity of HBME-1 and CD15 was investigated using 50 imprint smear cytological specimens obtained from thyroid lesions, including 13 FVPTC. The sensitivity and specificity of HBME-1 for FVPTC were 92% and 89%, respectively, while those of CD15 were 23% and 100%, respectively. In conclusion, HBME-1 is a sensitive marker of papillary carcinoma, including both usual type and FVPTC, in cytological specimens. Therefore, using HBME-1 immunocytochemistry in FNA cytology will lead to reduction of the incidence of false-negative diagnoses of FVPTC. Although CD15 is apparently inferior in terms of sensitivity for FVPTC, its excellent specificity will support the definitive diagnosis of thyroid malignancies, including FVPTC, after screening with HBME-1. © 2015 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.Pathology International 01/2015; 65(3). DOI:10.1111/pin.12252 · 1.59 Impact Factor
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ABSTRACT: There are several thyroid lesions that have been reported to be precursor, precancerous, or premalignant forms of, or predisposing factors for thyroid carcinoma. These lesions include normal thyroid with radiation history and chronic inflammation such as autoimmune thyroiditis, solid cell nest, hyperplastic adenomatous nodule, dyshormonogenetic goiter, follicular adenoma, atypical adenoma, borderline malignancy (follicular tumor of uncertain malignant potential and well-differentiated tumor of uncertain malignant potential), and some extremely low-grade thyroid neoplasms currently labeled as cancer including papillary microcarcinoma, capsular invasion only follicular carcinoma, and encapsulated papillary carcinoma. This article briefly reviews these lesions as possible precursor lesions of thyroid carcinomas, an important initial step of carcinogenesis or an early phase of progression in the multistep carcinogenesis theory.