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Diagnosis and reporting of follicular-patterned thyroid lesions by fine needle aspiration.

Faquin WC - Head Neck Pathol (2009)

Bottom Line: Based primarily upon the cytoarchitectural pattern, FNA is used as a screening test for follicular-patterned lesions to identify the majority of patients with benign nodules who can be managed without surgical intervention.A key element of this approach is the category "atypical cells of undetermined significance" (ACUS) which is used for those aspirates which cannot be easily classified as benign, suspicious, or malignant.The recommended follow-up for an ACUS diagnosis is clinical correlation and in most cases, repeat FNA sampling.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA. WFaquin@Partners.org

ABSTRACT
Over the past 3 decades, fine needle aspiration (FNA) has developed as the most accurate and cost-effective initial method for guiding the clinical management of patients with thyroid nodules. Thyroid FNA specimens containing follicular-patterned lesions are the most commonly encountered and include various forms of benign thyroid nodules, follicular carcinomas, and the follicular variant of papillary thyroid carcinoma. Based primarily upon the cytoarchitectural pattern, FNA is used as a screening test for follicular-patterned lesions to identify the majority of patients with benign nodules who can be managed without surgical intervention. The terminology and reporting of thyroid FNA results have been problematic due to significant variation between laboratories, but the recent multidisciplinary NCI Thyroid FNA State of the Science Conference has provided a seven-tiered diagnostic solution. A key element of this approach is the category "atypical cells of undetermined significance" (ACUS) which is used for those aspirates which cannot be easily classified as benign, suspicious, or malignant. Lesions in this category represent approximately 3-6% of thyroid FNAs and have a risk of malignancy intermediate between the "benign" category and the "suspicious for a follicular neoplasm" category. The recommended follow-up for an ACUS diagnosis is clinical correlation and in most cases, repeat FNA sampling.

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The follicular variant of papillary thyroid carcinoma is characterized by cells with pale chromatin, somewhat enlarged oval nuclei, and occasional longitudinal nuclear grooves in a background of variable amounts of colloid. (Papanicoloau stain)
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Fig3: The follicular variant of papillary thyroid carcinoma is characterized by cells with pale chromatin, somewhat enlarged oval nuclei, and occasional longitudinal nuclear grooves in a background of variable amounts of colloid. (Papanicoloau stain)

Mentions: The follicular variant of papillary thyroid carcinoma is the most common subtype of papillary thyroid carcinomas [5]. In FNA specimens, it can pose a diagnostic challenge due to the abundance of microfollicles or monolayer tissue fragments mimicking a follicular neoplasm. In fact, among those FNAs diagnosed as “suspicious for a follicular neoplasm” that are malignant in histologic follow-up, over 30% are identified as the follicular variant of papillary thyroid carcinoma [13, 14]. In contrast to the hyperchromatic chromatin seen in follicular neoplasms, the follicular variant of papillary thyroid carcinoma exhibits pale, powdery chromatin along with nuclear grooves and occasional intranuclear pseudoinclusions (Fig. 3). The cells tend to be round to oval and less pleomorphic than the conventional type of papillary carcinoma. Variable amounts of dense colloid are frequently seen in this variant, and multinucleated giant cells may also be identified. Usually the cytologic diagnosis of the follicular variant of papillary carcinoma is not difficult, but in a subset of cases, the nuclear features can be quite subtle resulting in misclassification of the lesion. Development of methods to detect RET/PTC rearrangements or point mutations of the BRAF gene in routine thyroid FNA samples may prove useful for solving this problem [15].Fig. 3


Diagnosis and reporting of follicular-patterned thyroid lesions by fine needle aspiration.

Faquin WC - Head Neck Pathol (2009)

The follicular variant of papillary thyroid carcinoma is characterized by cells with pale chromatin, somewhat enlarged oval nuclei, and occasional longitudinal nuclear grooves in a background of variable amounts of colloid. (Papanicoloau stain)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2807535&req=5

Fig3: The follicular variant of papillary thyroid carcinoma is characterized by cells with pale chromatin, somewhat enlarged oval nuclei, and occasional longitudinal nuclear grooves in a background of variable amounts of colloid. (Papanicoloau stain)
Mentions: The follicular variant of papillary thyroid carcinoma is the most common subtype of papillary thyroid carcinomas [5]. In FNA specimens, it can pose a diagnostic challenge due to the abundance of microfollicles or monolayer tissue fragments mimicking a follicular neoplasm. In fact, among those FNAs diagnosed as “suspicious for a follicular neoplasm” that are malignant in histologic follow-up, over 30% are identified as the follicular variant of papillary thyroid carcinoma [13, 14]. In contrast to the hyperchromatic chromatin seen in follicular neoplasms, the follicular variant of papillary thyroid carcinoma exhibits pale, powdery chromatin along with nuclear grooves and occasional intranuclear pseudoinclusions (Fig. 3). The cells tend to be round to oval and less pleomorphic than the conventional type of papillary carcinoma. Variable amounts of dense colloid are frequently seen in this variant, and multinucleated giant cells may also be identified. Usually the cytologic diagnosis of the follicular variant of papillary carcinoma is not difficult, but in a subset of cases, the nuclear features can be quite subtle resulting in misclassification of the lesion. Development of methods to detect RET/PTC rearrangements or point mutations of the BRAF gene in routine thyroid FNA samples may prove useful for solving this problem [15].Fig. 3

Bottom Line: Based primarily upon the cytoarchitectural pattern, FNA is used as a screening test for follicular-patterned lesions to identify the majority of patients with benign nodules who can be managed without surgical intervention.A key element of this approach is the category "atypical cells of undetermined significance" (ACUS) which is used for those aspirates which cannot be easily classified as benign, suspicious, or malignant.The recommended follow-up for an ACUS diagnosis is clinical correlation and in most cases, repeat FNA sampling.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Massachusetts General Hospital, Harvard Medical School, 55 Fruit Street, Boston, MA 02114, USA. WFaquin@Partners.org

ABSTRACT
Over the past 3 decades, fine needle aspiration (FNA) has developed as the most accurate and cost-effective initial method for guiding the clinical management of patients with thyroid nodules. Thyroid FNA specimens containing follicular-patterned lesions are the most commonly encountered and include various forms of benign thyroid nodules, follicular carcinomas, and the follicular variant of papillary thyroid carcinoma. Based primarily upon the cytoarchitectural pattern, FNA is used as a screening test for follicular-patterned lesions to identify the majority of patients with benign nodules who can be managed without surgical intervention. The terminology and reporting of thyroid FNA results have been problematic due to significant variation between laboratories, but the recent multidisciplinary NCI Thyroid FNA State of the Science Conference has provided a seven-tiered diagnostic solution. A key element of this approach is the category "atypical cells of undetermined significance" (ACUS) which is used for those aspirates which cannot be easily classified as benign, suspicious, or malignant. Lesions in this category represent approximately 3-6% of thyroid FNAs and have a risk of malignancy intermediate between the "benign" category and the "suspicious for a follicular neoplasm" category. The recommended follow-up for an ACUS diagnosis is clinical correlation and in most cases, repeat FNA sampling.

Show MeSH
Related in: MedlinePlus