Thyroid cytopathology reporting by the bethesda system: a two-year prospective study in an academic institution

Abstract

Background. The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has attempted to standardize reporting and cytological criteria in aspiration smears. Aims. The objective of this study was to analyze the thyroid cytology smears by TBSRTC, to determine the distribution of diagnostic categories and subcategories, to analyze cytological features, and to correlate the cytopathology with histopathology, wherever surgery was done. Materials and Methods. This was a prospective study of 225 fine needle aspirations (FNA) of thyroid nodules. All fine needle aspiration cytology (FNAC) diagnoses were classified according to the features given in the monograph of TBSRTC into nondiagnostic/unsatisfactory (ND/UNS), benign, atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS), follicular neoplasm/suspicious of a follicular neoplasm (FN/SFN), suspicious for malignancy (SFM), and malignant. Cytohistological correlation was done, when surgical material was available. Results. The distribution of various categories from 225 evaluated thyroid nodules was as follows: 7.2% ND/UNS, 80.0% benign, 4.9% AUS/FLUS, 2.2% FN, 3.5% SFM, and 2.2% malignant. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Conclusions. TBSRTC is an excellent reporting system for thyroid FNA. It also provides clear management guidelines to clinicians to go for follow-up FNA or surgery and also the extent of surgery.

Figure 1

(a) Benign follicular nodule. Photomicrograph showing monolayer sheets of evenly spaced follicular cells having a honeycomb-like arrangement (arrow) (Smear, Giemsa, 400x magnification). (b) Benign follicular nodule. Photomicrograph showing globular mass of colloid with superimposed follicular cells (thick arrow) mixed with monolayer sheet of follicular cells (thin arrow) against the background of colloid and blood (Smear, Giemsa, 400x magnification). (c) Benign follicular nodule. Photomicrograph showing follicular cells arranged in sheets (honeycomb-like) (thin arrow) mixed with macrophages (thick arrow) against the background of colloid (Smear, Giemsa, 400x magnification).

Figure 2

(a) Lymphocytic (Hashimoto) thyroiditis. Photomicrograph showing polymorphous lymphoid population (Smear, Giemsa, 400x magnification). (b) Lymphocytic (Hashimoto) thyroiditis. Photomicrograph showing lymphohistiocytic aggregates in lymphocytic (Hashimoto) thyroiditis (Smear, Giemsa, 400x magnification).

Figure 3

(a) Granulomatous (subacute) thyroiditis. Photomicrograph showing clusters of epithelioid histiocytes (thick arrow) mixed with benign follicular cells (thin arrow) (Smear, Giemsa, 400x magnification). (b) Granulomatous (subacute) thyroiditis. Photomicrograph showing many multinucleated giant cells against the background of colloid and blood (Smear, Giemsa, 400x magnification).

Figure 4

(a) Atypia of undetermined significance. Photomicrograph showing prominent microfollicles in a moderately cellular specimen (Smear, Giemsa, 400x magnification). (b) Atypia of undetermined significance. Photomicrograph showing sparsely cellular specimen with a predominance of microfollicles (Smear, Giemsa, 400x magnification).

Figure 5

Follicular neoplasm/suspicious for a follicular neoplasm. Photomicrograph showing a highly cellular aspirate composed of uniform follicular cells arranged in crowded clusters and microfollicles (Smear, Giemsa, 400x magnification).

Figure 6

Suspicious for lymphoma. Photomicrograph showing a hemodiluted sample comprising exclusively lymphoid cells (Smear, Giemsa, 400x magnification).

Figure 7

(a) Papillary thyroid carcinoma. Photomicrograph showing highly cellular specimen composed of numerous monolayer sheets and occasional papillary-like fragments and “stringy,” “ropy” colloid (arrow) (Smear, Papanicolaou stain, 400x magnification). (b) Papillary thyroid carcinoma. Photomicrograph showing “stringy” colloid (thick arrow) and intranuclear cytoplasmic inclusions (thin arrow) (Smear, Giemsa, 1000x magnification). (c) Papillary thyroid carcinoma. Photomicrograph showing multinucleated giant cell engulfing sticky colloid (arrow) in a case of papillary thyroid carcinoma (Smear, Papanicolaou stain, 400x magnification). (d) Papillary thyroid carcinoma. Photomicrograph showing longitudinal nuclear grooves (thin long arrow) and micronucleoli (thin short arrows) (Smear, Papanicolaou stain, 1000x magnification). (e) Papillary thyroid carcinoma, oncocytic variant. Photomicrograph showing the neoplasm composed throughout of oncocytic (Hürthle-like) cells that have abundant granular cytoplasm. Intranuclear cytoplasmic inclusions are visible (arrow) (Smear, Giemsa, 1000x magnification).

Figure 8

(a) (100x magnification) and (b) (1000x magnification) Medullary thyroid carcinoma. Photomicrographs showing predominantly cohesive, syncytial-like clusters with few isolated plasmacytoid cells (Smear, Giemsa stain).