Follicular Neoplasms of the Thyroid: What to Recommend

Abstract

Follicular neoplasms of the thyroid are usually diagnosed following fine-needle aspiration (FNA) biopsy of a dominant thyroid nodule. An FNA diagnosis of a follicular neoplasm represents a heterogeneous group of lesions including benign follicular hyperplasia, follicular adenomas, follicular carcinomas, and the follicular variant of papillary carcinoma. Hürthle cell neoplasms are also often included in this group. Because the criteria for malignancy in both follicular and Hürthle cell neoplasms requires vascular or capsular invasion seen on permanent histology, the majority of these patients undergo surgical resection. Intraoperative frozen section analysis of follicular neoplasms rarely renders informative information. Approximately 20% of these lesions prove to be malignant and for lesions greater than 1.0 cm in size, the majority of surgeons and endocrinologists recommend a total thyroidectomy. Postoperative treatment generally includes therapeutic doses of 131I for follicular carcinomas.

Effect of nodule size on the reliability of fine-needle aspiration biopsy in thyroid nodules

“…The sensitivity of FNAB was reported as ranging from 58.3% to 98% and the specificity of FNAB as ranging from 72% to 100% in the retrospective analysis of 37,895 patients issued by Ravetto et al in 2000, and in studies by Cap et al, Mandell et al, Sankhla et al, and Bennedbaek et al (22)(23)(24)(25)(26). The calculations in the majority of these publications were performed by excluding suspicious lesions from the studies.…”

“…Screening of malignancy in follicular lesions is usually not possible only on the basis of cytology; it requires diagnostic lobectomy (23).…”

Expression of Matrix Metalloproteinase-2, but not Caspase-3, Facilitates Distinction between Benign and Malignant Thyroid Follicular Neoplasms

“…Regarding the fact that 5-10% of the population will develop a clinically significant thyroid nodule during their lifetime (Mazzaferi, 1993;Barden et al, 2003) and that by fine needle aspiration biopsy approximately 20% of thyroid nodules are follicular neoplasms (Carling & Udelsman, 2005), methods for distinguishing between adenoma and carcinoma would obviate many unnecessary thyroid surgeries.…”

“…Thyroid tumors with a follicular growth pattern include a broad range of lesions from benign hyperplastic nodules to malignant neoplasms (Carling & Udelsman, 2005). Follicular thyroid adenoma (FTA), a benign encapsulated tumor with evidence of follicular cell differentiation, is the most common thyroid neoplasm (Rosai, 2011).…”

Predictive Factors of Malignancy in Thyroid Nodules Diagnosed as Follicular Neoplasm or Hürthle Cell Neoplasm on FNA

“…(3)(4)(5)(6) FN is characterized by a predominance of follicular epithelial cells forming microfollicles with a paucity of colloid and encompasses benign follicular hyperplasia, follicular adenoma, follicular carcinoma, and the follicular variant of PTC. (1,7) HCN denotes a set of tumors composed of 75% or greater Hürthle (oncocytic) cells derived from follicular epithelium, which is characterized cytologically as a large cell with abdundant eosinophilic, granular cytoplasm and a large hyperchromatic nucleus with a prominent nucleolus. (1,3,8) A variety of thyroid neoplasms are characterized as having oncocytic cytology.…”