Diagnosis of “follicular neoplasm”: A gray zone in thyroid fine‐needle aspiration cytology

Abstract

The thyroid fine-needle aspiration (FNA) diagnosis of "follicular neoplasm" does not differentiate between a benign and malignant tumor. Often cases diagnosed as "follicular or Hürthle-cell neoplasm" undergo surgical excision for further characterization. The aim of this study was to identify clinical features that may help in predicting malignancy in patients with an FNA diagnosis of follicular neoplasm. One hundred eighty-four cases in 167 patients were diagnosed as "follicular neoplasm" among 1,024 thyroid FNA evaluated with on-site interpretation from 1998-2000. The cases were evaluated for the following variables: histologic diagnosis, age, sex, and size of the nodule. One hundred thirty-nine patients were female, and 28 were male (age range, 23-80 yr). Among 122 patients (67%) undergoing surgical excision (lobectomy, 96; total thyroidectomy, 26), malignancy was identified in 37 cases (31%). Nonpapillary (follicular/Hürthle) carcinoma was diagnosed in 11 (9%), follicular variant of papillary carcinoma in 25, and medullary carcinoma in 1 case. The risk of malignancy was greater in males (47% vs. 29%, P < 0.0004) than females, in nodules measuring 3 cm or more (55% vs. 23%, P < 0.0001), than in nodules measuring less than 3 cm, and in patients 40 or more yr old (20% vs. 10%, P = 0.0001) than in patients younger than 40 years. The diagnosis "follicular neoplasm" is indeterminate, and the majority of cases (70% in the current study) are benign. However, clinical features, including gender, nodule size, and age, can be a part of the decision analysis in selecting patients for surgery.

Sonographically guided fine needle aspiration of thyroid nodule: Discrepancies between cytologic and histopathologic findings

“…12,21 In an attempt to avoid unnecessary surgery of thyroid nodules with follicular neoplasm, some authors have further stratified the indeterminate thyroid aspirates into high-and low-risk groups for a malignancy based on clinical parameters. [24][25][26] Baloch et al 24 reported male sex, age >40 years, and a nodule size >3 cm to be significantly associated with a higher likelihood of a malignancy. Similarly, Davis et al 25 added a history of neck irradiation to those parameters associated with a risk of a malignancy, including size >3 cm and age >50 years; however, sex and family history of goiter or neoplasm were not predisposing factors.…”

Diagnostic and extent of disease multigene assay for malignant thyroid neoplasms

“…1,2,19 Using a real-time quantitative RT-PCR multigene assay of novel diagnostic markers for differentiated thyroid cancer, we were able to distinguish between benign and malignant thyroid neoplasms with a high accuracy. Furthermore, this multigene assay that included 3 markers of extent of disease was useful for segregating low-risk versus high-risk (AMES system) differentiated thyroid cancers and correlated with other staging systems (AGES, MACIS, and EORTC).…”

Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Taskforce

“…Among solitary thyroid nodules with an indeterminate ("suspicious," "follicular neoplasm," or Hürthle cell neoplasm) biopsy, the risk of malignancy is approximately 20% (90)(91)(92). For solitary nodules that are repeatedly nondiagnostic on biopsy, the risk of malignancy is unknown but is probably closer to 5%-10% (29).…”