"Cellular adenomatoid nodules" of the thyroid: review of 219 fine-needle aspirates

A Cytohistologic Correlation Study of Thyroid Lesions: Evaluation of Diagnostic Accuracy and Pitfalls of Fine Needle Aspiration Cytology

Background Only about 5% of palpable thyroid nodules are malignant; the rest are entirely benign. In order to reduce the number of unnecessary treatments and properly identify situations that need surgical intervention, it is essential to distinguish between benign and malignant lesions prior to surgery. There exists a "grey zone" in thyroid cytology characterized by a significant decrease in diagnostic accuracy, making it difficult to precisely classify the lesion and leading to discrepancies. Aims and objectives The study aims to accomplish the following objectives: (1) assess the prevalence of thyroid lesions according to age and sex; (2) evaluate the accuracy of the fine needle aspiration cytology (FNAC) in diagnosing thyroid conditions; and (3) investigate the causes of cytohistological discordance within the context of this study. Materials and methods In our five-year study of thyroid lesions, 125 cases were studied for cytohistological correlation. Discrepant and likened FNAs were classified according to the diagnostic findings. A review of the cytological smears and histological sections was conducted. Results The cytological diagnoses were correlated with histopathology in 109 cases (90.83%). A total of 11 cases (09.16%) were discrepant. There were no false positives (FPs). The causes of false negative (FN) diagnoses in our study can be attributed to geographic misses and failure to recognize dual pathologies. Conclusion FNA is a very precise and time-saving technique for the diagnosis and subsequent management of palpable thyroid nodules. Patients having thyroidectomies have a much higher malignant yield, and the frequency of procedures performed on the thyroid is decreased. When FNA interpretation based on strict specimen sufficiency standards is considered along with clinical and imaging findings, the occurrence of FN and FP diagnoses is expected to decrease.

Malignant human thyroid neoplasms associated with blood parasitic (haemosporidian) infection

Investigation of archival cytological material obtained by cytologists during fine-needle aspiration biopsy in follicular, papillary, and medullary human thyroid cancers revealed haemosporidian (blood parasitic) infection. Haemosporidian infection was detected as exo- and intraerythrocytic stages of development in thyrocytes schizogony. The exoerythrocytic stage of development is represented as microschizonts in a thyroid needle biopsy specimen. Probably, blood parasitic infection is the common etiology for these pathologies. All biopsy material in medical laboratories was stained with RomanowskyGiemsa stain. To clarify the localization of nuclei (DNA) of thyrocytes and nuclei (DNA) of haemosporidian infection in cytological material following investigation of the entire set of smears, a selective series of original archival smears was stained (restained) with a Feulgen/Schiff reagent. Staining of smears with RomanowskyGiemsa stain is an adsorption method that enables re-use of the same smears for staining with a Feulgen/Schiff reagent where the fuchsin dye, after DNA hydrolysis by hydrochloric acid, is incorporated into DNA and stains it in redviolet (crimsonlilac) color. An intentionally unstained protoplasm of blood parasitic infection was present as a light band around erythrocyte nuclei. In follicular thyroid cancer, Feulgen staining of thyrocytes revealed nuclear DNA and parasitic DNA (haemosporidium nuclei) as point inclusions and rings and diffusely distributed in the thyrocyte cytoplasm. The thyrocyte cytoplasm and nuclei were vacuolated, with thyrocyte nuclei being deformed, flattened, and displaced to the cell periphery. The erythrocytes, which were initially stained with eosin (orange color), contained haemosporidian nuclei (DNA). In some cases, endoglobular inclusions in thyrocytes and erythrocytes were of the same size. In papillary thyroid cancer, we were able to localize the nuclear DNA of thyrocytes and the parasitic DNA as point inclusions and diffusely distributed in the thyrocyte cytoplasm. Two or more polymorphic nuclei may eccentrically occur in the hyperplastic cytoplasm. Haemosporidian microschizonts occurred circumnuclearly in thyrocytes and as an exoerythrocytic stage in the blood. The erythrocyte cytoplasm contained redviolet polymorphic haemosporidian nuclei (DNA). In medullary thyroid cancer, the hyperplastic cytoplasm of thyrocytes contained eccentrically located nuclei (DNA) of thyrocytes and small haemosporidian nuclei (DNA), which may occupy the whole thyrocyte. There were thyrocytes with vacuolated cytoplasm and pronounced nuclear polymorphism. The size of hyperplastic nuclei was several times larger than that of normal thyrocyte nuclei. The color of stained cytoplasmic and nuclear vacuoles of thyrocytes was less redviolet compared with that of surrounding tissues, which probably indicates the presence of parasitic DNA in them. The haemosporidian nuclear material in erythrocytes is represented by polymorphic nuclei, which may indicate the simultaneous presence of different pathogen species and/or generations in the blood. Intracellular parasitism of haemosporidian infection in thyrocytes (schizogony) associated with three thyroid cancers leads to pronounced cytoplasmic hyperplasia, cytoplasmic vacuolization, and nuclear vacuolization of the thyrocyte, followed by impaired secretory function. Multinucleated thyrocytes with incomplete cytokinesis appear. The absence of lytic death of the affected thyrocytes indicates that the contagium is able to control apoptosis and influence physiological functions of the cell. There is deformation of the nuclei, which leads to a decrease in their size, their flattening and displacement to the cell periphery, with high risk of DNA mutations and deletions in affected cells, reaching a neoplastic level.

Differential regional importance mapping for thyroid nodule malignancy prediction with potential to improve needle aspiration biopsy sampling reliability

Objective

Existing guidelines for ultrasound-guided fine-needle aspiration biopsy lack specifications on sampling sites, but the number of biopsies improves diagnostic reliability. We propose the use of class activation maps (CAMs) and our modified malignancy-specific heat maps that locate important deep representations of thyroid nodules for class predictions.

Methods

We applied adversarial noise perturbations to the segmented concentric "hot" nodular regions of equal sizes to differentiate regional importance for the malignancy diagnostic performances of an accurate ultrasound-based artificial intelligence computer-aided diagnosis (AI-CADx) system using 2,602 retrospectively collected thyroid nodules with known histopathological diagnosis.

Results

The AI system demonstrated high diagnostic performance with an area under the curve (AUC) value of 0.9302 and good nodule identification capability with a median dice coefficient >0.9 when compared to radiologists' segmentations. Experiments confirmed that the CAM-based heat maps reflect the differentiable importance of different nodular regions for an AI-CADx system to make its predictions. No less importantly, the hot regions in malignancy heat maps of ultrasound images in comparison with the inactivated regions of the same 100 malignant nodules randomly selected from the dataset had higher summed frequency-weighted feature scores of 6.04 versus 4.96 rated by radiologists with more than 15 years of ultrasound examination experience according to widely used ultrasound-based risk stratification American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TI-RADS) in terms of nodule composition, echogenicity, and echogenic foci, excluding shape and margin attributes, which could only be evaluated on the whole rather than on the sub-nodular component levels. In addition, we show examples demonstrating good spatial correspondence of highlighted regions of malignancy heat map to malignant tumor cell-rich regions in hematoxylin and eosin-stained histopathological images.

Conclusion

Our proposed CAM-based ultrasonographic malignancy heat map provides quantitative visualization of malignancy heterogeneity within a tumor, and it is of clinical interest to investigate in the future its usefulness to improve fine-needle aspiration biopsy (FNAB) sampling reliability by targeting potentially more suspicious sub-nodular regions.

An artificial intelligence ultrasound system's ability to distinguish benign from malignant follicular-patterned lesions

OBJECTIVES

To evaluate the application value of a generally trained artificial intelligence (AI) automatic diagnosis system in the malignancy diagnosis of follicular-patterned thyroid lesions (FPTL), including follicular thyroid carcinoma (FTC), adenomatoid hyperplasia nodule (AHN) and follicular thyroid adenoma (FTA) and compare the diagnostic performance with radiologists of different experience levels.

METHODS

We retrospectively reviewed 607 patients with 699 thyroid nodules that included 168 malignant nodules by using postoperative pathology as the gold standard, and compared the diagnostic performances of three radiologists (one junior, two senior) and that of AI automatic diagnosis system in malignancy diagnosis of FPTL in terms of sensitivity, specificity and accuracy, respectively. Pairwise t-test was used to evaluate the statistically significant difference.

RESULTS

The accuracy of the AI system in malignancy diagnosis was 0.71, which was higher than the best radiologist in this study by a margin of 0.09 with a p-value of 2.08×10^-5. Two radiologists had higher sensitivity (0.84 and 0.78) than that of the AI system (0.69) at the cost of having much lower specificity (0.35, 0.57 versus 0.71). One senior radiologist showed balanced sensitivity and specificity (0.62 and 0.54) but both were lower than that of the AI system.

CONCLUSIONS

The generally trained AI automatic diagnosis system can potentially assist radiologists for distinguishing FTC from other FPTL cases that share poorly distinguishable ultrasonographical features.

Effect of BRAF V600E mutation detection of fine-needle aspiration biopsy on diagnosis and treatment guidance of papillary thyroid carcinoma

OBJECTIVE

The aim of this study was to evaluate the diagnostic value of detection of BRAF V600E mutation in the fine-needle aspiration cytology (FNAC) specimens of thyroid nodules and the relationship between BRAF V600E mutation and the clinicopathological characteristics of papillary thyroid carcinoma (PTC).

METHODS

A total of 252 patients who underwent initial thyroid surgery were retrospectively analysed. All the patients underwent a preoperative FNAC at our institution, and the thyroid puncture cell fluid was used for both the cytological diagnosis and BRAF V600E mutational analysis using quantitative polymerase chain reaction. The Cochran-Mantel-Haenszel test was used to evaluate the diagnostic value of BRAF V600E mutation in FNAC fluid in diagnosing PTC. The association between BRAF V600E mutation and the clinicopathological parameters of PTC was analysed using the χ² test.

RESULTS

Through FNAC, 21 (8%), 60 (24%), and 171 (68%) cases were cytologically diagnosed as benign, indeterminate, and malignant, respectively. Postoperatively, 242 cases were histopathologically diagnosed as PTCs and 10 as goitre nodules. In the FNAC samples, 12 (57 %) of the 21 benign, 48 (80 %) of the 60 indeterminate, and 152 (88.9 %) of the 171 malignant cases showed BRAF V600E mutation. The histopathological diagnosis was used as the gold standard. The sensitivity and specificity of BRAF V600E mutational analysis in the FNAC samples for the diagnosis of PTC were 91.7 % and 100 % in benign, 82.8 % and 100 % in the indeterminate, and 89.4 % and 100 % in the malignant cases, respectively.

CONCLUSION

BRAF V600E mutational analysis in FNAC samples of thyroid nodules can be used an effective supplementary diagnostic method at our institution. However, BRAF V600E mutation was not associated with aggressive characteristics in PTC.

Current role and value of fine-needle aspiration in nodular goitre

Thyroid nodules are common and, depending on the detection technique used, can affect 50% or greater of the population. The primary diagnostic test to assess the nature of these nodules is fine-needle aspiration cytology. Most thyroid nodules are benign and often are multiple. However, the morphology of these nodules may mimic neoplasms showing features such as papillary growth, micro-follicles and even oncocytic metaplasia. Lesions with these features may be considered indeterminate for neoplasm or malignancy, and often require surgical excision to define their nature. The role of cytopathology in this area is to screen those definitely benign nodules, thus preventing surgery and reassuring both the patient and the clinician. In this review, we demonstrate many of the morphological manifestations of nodular goiter and stress the necessity of careful preparatory techniques. Although the past several years have witnessed the development of molecular testing to refine diagnostic cytology in the thyroid, it is still the role of the cytopathologist to identify those "indeterminant" nodules which should be tested. Thus, the cytopathologist contributes both an essential diagnostic and an important cost saving role which hopefully will continue in the future.

Second opinion in thyroid fine-needle aspiration biopsy by the Bethesda system

The present study was designed to determine the impact of secondary review of thyroid fine-needle aspiration (FNA) biopsy on surgical management. A retrospective review of patients referred to our institution with a thyroid FNA biopsy was conducted. Cytologic diagnoses from the report at our center and the referring institution were re-categorized by the Bethesda System for Reporting Thyroid Cytopathology. The rate of diagnostic disagreement was evaluated between Primary Diagnosis (PD) and Second Opinion Diagnosis (SOD), and the clinicopathologic correlations and the number of cases that prompted changes in treatment as a result of diagnostic disagreement were analyzed. 1499 patients meeting our study criteria were enrolled in this study. Diagnostic disagreement comprised 394 cases (26.3%). In the case of diagnostic disagreement, SOD was supported on clinicopathologic follow-up in 271 cases (68.8%), of which a change in management was made in 54 (13.7%) cases, and PD was supported in 93 (23.6%) cases, of which a change in management was made in 13 (3.3%) cases. By the second opinion, 65 (4.5%) patients received proper management, and 14 (1.0%) patients received superfluous management. Wide use of secondary cytopathologic review of thyroid FNA specimens from referring institutions was recommended.

Group consensus review minimizes the diagnosis of "follicular lesion of undetermined significance" and improves cytohistologic concordance

We conducted a group consensus review of thyroid aspirates that were previously interpreted as "atypia of undetermined significance/follicular lesion of undetermined significance" (AUS/FLUS) and followed by surgical interventions. The study aimed to investigate if consensus review would minimize the diagnosis of AUS/FLUS with an optimal interobserver agreement and also promote a better cytohistologic concordance. A group of reviewers who were blinded to the corresponding histologic findings simultaneously evaluated a total of 50 aspirates at a multiheaded light microscope. Using the Bethesda System for Reporting Thyroid Cytopathology as a guideline, a consensus interpretation was reached upon review of each aspirate. Interobserver agreement was calculated and recorded. The cytohistologic correlation was then performed between the consensus interpretation and the corresponding histologic diagnosis. The consensus review reclassified 26 (52%) aspirates as non-neoplasia/benign, 10 (20%) as follicular neoplasm/suspicious for a follicular neoplasm, 1 (2%) as papillary thyroid carcinoma, and 2 (4%) as nondiagnostic. Eleven (22%) aspirates remained AUS/FLUS. The interobserver agreement across the five diagnostic categories ranged from 71.6% to 100% with an average level of 88.8%. Cytohistologic concordance was achieved in 24 of 26 (92.3%) and 9 of 11 (81.8%) aspirates that were reclassified as non-neoplasia/benign and neoplasia/malignancy, respectively. A diagnostic accuracy of 89.2% (33/37) was obtained in reclassified cases. In conclusion, the group consensus review minimized AUS/FLUS, offered an optimal level of interobserver agreement, and most importantly, promoted excellent cytohistologic concordance in reclassified cases and, therefore, could play a substantial role in the future in reducing reaspiration and/or unnecessary surgeries.

Minimizing the diagnosis of "follicular lesion of undetermined significance" and identifying predictive features for neoplasia

We used proposed standard morphologic criteria as a guideline to conduct a 10-year retrospective review of thyroid fine-needle aspiration specimens that were originally interpreted as "follicular lesion of undetermined significance" and followed by surgical intervention. We sought to investigate whether the indeterminate diagnosis could be minimized by assessing various cytomorphologic features and identifying the features predictive of neoplasia. Using the standard morphologic criteria, we semi-quantitatively assessed a total of 24 cytomorphologic features in 123 aspirates and recorded an overall interpretation on completion of the review. Cyto-histologic correlation was evaluated and logistic regression model was performed to identify cytomorphologic features predictive of neoplasia. Although 32 of 123 aspirates remained in the indeterminate category, the retrospective review reclassified 64 aspirates as non-neoplasia and 27 aspirates as neoplasia. Histologic confirmation was achieved in 47 (73.4%) non-neoplastic and 15 (55.6%) neoplastic aspirates with a diagnostic accuracy of 68.1%. Furthermore, our analysis demonstrated that neoplasia is positively associated with the presence of syncytial tissue fragments, isolated microfollicles, follicles with scalloped borders, scant cytoplasm, irregular nuclear membranes, nuclear overlapping, coarse chromatin, and increased cellularity. On the contrary, the presence of honeycombing tissue fragments, background colloid, and histiocytes inversely correlated with neoplasia. Overall, using proposed standard morphological criteria can minimize the diagnosis of "follicular lesion of undetermined significance," and allow for more accurate cyto-histologic correlation, and thereby playing a substantial role in reducing unnecessary surgical intervention.

Hürthle cell neoplasm: correlation of gray-scale and power Doppler sonographic findings with gross pathology

BACKGROUND

To describe gray-scale and power Doppler (PD) sonographic (US) findings of Hürthle cell neoplasms (HCNs) of the thyroid gland, and to determine if there is any correlation between US and gross pathologic features.

METHOD

This retrospective study included 30 pathologically proven HCNs in 30 subjects who underwent preoperative gray-scale and PD US examinations. The size, shape, margin, echogenicity, echotexture, presence or absence of cystic change, calcifications and halo sign, and vascularity at PD US were evaluated.

RESULT

The longest diameter of HCNs ranged from 12 mm to 63 mm. The shape and margins of the mass were ovoid and smooth, respectively, in all cases. The echogenicity was hypoechoic, isoechoic, hyperechoic, or mixed in 43.3%, 33.3%, 10.0%, and 13.3%, respectively. The echotexture was heterogeneous in 73.3% and homogeneous in 26.7%. Cystic change was present in 56.7% and involved less than 25% of the volume of the mass in 50.0% and 26-50% of the volume in 6.7%. Coarse calcifications were present in 20.0%. Halo sign was present in all cases. The vascularity was combined peri- and intranodular in all cases: predominantly intranodular in 50.0%, predominantly perinodular in 46.7%, and of the "inferno" type in 3.3%. All HCNs were encapsulated on gross pathologic examination.

CONCLUSION

Although many of the US features we observed were nonspecific, HCNs tend to have a halo sign and combined peri- and intranodular vascularity on US, which raises the possibility of an association. The US halo sign corresponds to tumor capsule ongross pathologic examination.

Absence of microfollicular basement membrane: a new indicator in the diagnosis of follicular carcinoma thyroid

The thyroid follicles represent a biological continuum. Each follicle is closely related to the follicle that is next to it. The important feature of a follicular carcinoma is a microfollicular pattern. We report a case of follicular carcinoma in a 48-year-old female that demonstrates microfollicles which are larger in size and contain more number of follicular cells in cytologic smears (20-29 cells) in contrary to the literature definition of microfollicles containing approximately 6-12 cells. We also demonstrate absence of basement membranes in these microfollicles in histologic sections by Silver Methanamine Stain, which may be an indicator to search for vascular and capsular invasion. This case report also describes postoperative positron emission tomography scan findings.

Detection of BRAFV600E mutation on fine needle aspiration specimens of thyroid nodule refines cyto-pathology diagnosis, especially in BRAF600E mutation-prevalent area

BACKGROUND

Between 10 and 30% of the fine needle aspiration biopsies (FNABs) of thyroid nodules are diagnosed as 'indeterminate'. A molecular diagnostic method is needed to reduce unnecessary surgery in this group. In Korea, most thyroid cancer is the classic papillary type and the BRAF(V600E) mutation is highly prevalent.

AIM

To evaluate the role of pre-operative detection of BRAF(V600E) mutation in the FNAB specimens of thyroid nodules in a BRAF(V600E) mutation-prevalent geographical area.

PATIENTS AND METHODS

In 137 specimens of FNAB (107 papillary thyroid carcinomas (PTC); 3 follicular thyroid carcinomas (FTC); 2 undifferentiated thyroid carcinomas; 25 benign lesions), both direct DNA sequencing and PCR-RFLP were used for detecting the BRAF(V600E) mutation. The sensitivity and specificity were calculated. We analysed the association between BRAF(V600E) mutation and the clinico-pathological parameters.

RESULTS

The BRAF(V600E) mutation was present in 93 (83%) of 112 thyroid cancers. Direct DNA sequencing showed a sensitivity of 83.0% and a specificity of 96.0%. The sensitivity and specificity of PCR-RFLP were 78.6% and 80.0%, respectively. Among 25 cases with indeterminate FNAB cytology, 8 patients had malignant lesions (5 PTC and 3 FTC). Three (60%) of 5 PTCs and 1 out of 17 benign lesions had BRAF(V600E) mutation (only one false positive case and the definitive pathology showed atypical nodular hyperplasia that could be a premalignant lesion). The diagnostic accuracy of this molecular method in only the 25 indeterminate nodules was 76% (19/25). No mutation was found in 3 FTCs. Among 107 PTCs, there was no significant association of the BRAF(V600E) mutation with the known risk factors.

CONCLUSION

Detection of the BRAF(V600E) mutation in FNAB specimens refines the FNAB-cytology diagnosis, especially in a BRAF(V600E) mutation-prevalent area. Direct DNA sequencing was a more reliable method than PCR-RFLP for detecting the BRAF(V600E) mutation with a high sensitivity and specificity.

Interobserver variability with the interpretation of thyroid FNA specimens showing predominantly Hürthle cells

Fine-needle aspiration (FNA) is used for the diagnosis and triaging of thyroid lesions. Recently, it has been shown that the pathologic interpretation of selected thyroid specimens can show a high degree of interobserver variability (IV). Because Hürthle cells may be seen in neoplastic and nonneoplastic disease, we investigated whether pathologists consistently interpret FNA specimens from these lesions. In the present study, 22 FNA specimens that showed Hürthle cells as the predominant cell type were reviewed by 7 pathologists. Cytologic features were assessed semiquantitatively. IV was calculated, and individual case diagnoses were compared with cytologic features. IV was high before diagnoses were collapsed into like diagnoses and triage recommendations (k = 0.17, 0.44, and 0.51, respectively). Overall cellularity, number of Hürthle cells, and number of lymphocytes all correlated with collapsed diagnostic agreement, and the number of air-dried rapid Romanowsky-stained slides, overall cellularity, number of Hürthle cells, and number of lymphocytes all correlated with collapsed triage recommendations.

Is thyroid follicular cancer in Japanese caused by a specific t(2; 3)(q13; p25) translocation generating Pax8-PPAR gamma fusion mRNA?

A recent western study reports that t(2; 3)(q13; p25) translocation resulting in the expression of the Pax8-PPAR gamma fusion gene in patients with thyroid follicular carcinoma (FTC) occurs with high incidence (63%). Furthermore, the products of the fusion gene were shown to suppress the function of PPAR gamma in a predominantly negative manner, conferring them with an oncogenic potential. We examined the expression of this fusion gene in FTC in Japanese patients. From 1989 to 2000, six cases with FTC were surgically treated at our institute. In these carcinoma samples, the expression of mRNAs for the Pax8-PPAR gamma fusion product was analyzed by nested RT-PCR. Their expression was also studied in other thyroid nodules (12 adenomatous goiters, 12 follicular adenomas, 12 papillary carcinomas and 12 normal thyroid tissues) obtained at surgery during the same period. Pax8-PPAR gamma fusion mRNA was not detected in any FTC samples nor in the other samples. Furthermore, none of the 6 FTCs, one follicular adenoma or one normal thyroid analyzed by fluorescence in situ hybridization (FISH) exhibited Pax8-PPAR gamma gene fusion. These findings are in contrast to previous reports and indicate that ethnic background may affect the translocation.

Management of simple nodular goiter: current status and future perspectives

The simple nodular goiter, the etiology of which is multifactorial, encompasses the spectrum from the incidental asymptomatic small solitary nodule to the large intrathoracic goiter, causing pressure symptoms as well as cosmetic complaints. Its management is still the cause of considerable controversy. The mainstay in the diagnostic evaluation is related to functional and morphological characterization with serum TSH and (some kind of) imaging. Because malignancy is just as common in patients with a multinodular goiter as patients with a solitary nodule, we support the increasing use of fine-needle aspiration biopsy (cytology). Most patients need no treatment after malignancy is ruled out. In case of cosmetic or pressure symptoms, the choice in multinodular goiter stands between surgery, which is still the first choice, and radioiodine if uptake is adequate. In addition to surgery, the solitary nodule, whether hot or cold, can be treated with percutaneous ethanol injection therapy. If hot, radioiodine is the therapy of choice. Randomized studies are scarce, and the side effects of nonsurgical therapy are coming into focus. Therefore, the use of the optimum option in the individual patient cannot at present be based on evidence. However, we are of the view that levothyroxine, although widely used, should no longer be recommended routinely for this condition. Within a few years, the introduction of recombinant human TSH and laser therapy may profoundly alter the nonsurgical treatment of simple nodular goiter.

The accuracy of fine-needle aspiration biopsy and frozen section in patients with thyroid cancer

A total of 1076 patients with thyroid nodules were reviewed. The accuracy of fine needle aspiration biopsy (FNAB) and frozen section (FS) were compared and clinical risk factors were analyzed. Our results indicate that 67.9% are benign and 32.1% are malignant with the predominance of papillary thyroid cancer (75.1%). Overall diagnostic accuracy for FNAB and FS were 90.8%-91.2% and 89.1%-90.5%, respectively. There were no significant differences between the diagnostic accuracy on FNAB and FS in all tumors except the follicular adenoma and carcinoma. The diagnostic accuracy of FS was higher than FNAB in patients with follicular adenoma (89.3% vs. 58.9%, p < 0.001) and but lower than FNAB in patients with follicular carcinoma (46.2% vs. 92.3%, p < 0.001). In conclusion, FNAB is cost effective in the preoperative evaluation of thyroid nodule. FS could be eliminated in most cases except with follicular and Hürthle cell neoplasms. FS is valuable when result of FNAB is suspicious or unavailable. FS is more appropriate in deciding the extent of thyroidectomy in follicular neoplasm and FNAB is more reliable initial approach to surgery in patients with Hürthle cell neoplasm. Clinical risk factors may help in selecting patients for surgery but cannot exceed FS in deciding the extent of thyroidectomy in patients with follicular and Hürthle cell neoplasms.

A pathologist trying to help endocrinologists to interpret cytopathology reports from thyroid aspirates

Fine-needle aspiration has become the diagnostic tool of choice in the initial evaluation of thyroid nodules. As a cytopathologist who has been performing fine-needle aspirations for over 25 yr at a university hospital and for the last 3 yr at the largest not-for-profit hospital in the Washington, D.C. area, I have seen increasing demand for this service. However, there is also discontent with the cytopathology reports issued by numerous laboratories. Pathologists have to standardize and simplify their reports so that they will be more meaningful to the referring physician. Endocrinologists should communicate their needs to the pathologists and insist on clear, succinct, and prompt diagnoses.

Diagnosis of "follicular neoplasm": a gray zone in thyroid fine-needle aspiration cytology

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.

Follicular-patterned lesions of the thyroid: the bane of the pathologist

This review focuses on follicular-patterned lesions of the thyroid gland and their differential diagnosis. Included are a discussion of the features differentiating follicular adenoma from adenomatous or hyperplastic nodule and follicular adenoma from follicular carcinoma and the follicular variant of papillary thyroid carcinoma. The cytologic and histologic characteristics are described, and criteria for diagnosing the major follicular lesions are reviewed.

Role of ultrafast Papanicolaou-stained scrape preparations as an adjunct to frozen sections in the surgical management of thyroid lesions

OBJECTIVE

To assess the value of intraoperative cytology on scrape preparations of thyroid lesions.

METHODS

We conducted a retrospective review of 73 cases of various thyroid lesions in which ultrafast Papanicolaou-stained scrape preparations were performed. Frozen sections were performed in 19 cases (26%). Fine-needle aspiration diagnosis was available in 65 cases. The correlation between the scrape diagnosis and the final diagnosis was analyzed.

RESULTS

The agreement rate between the scrape diagnosis and the final diagnosis was 89%. All cases diagnosed as suspicious for papillary thyroid carcinoma on fine-needle aspiration were definite for malignant papillary carcinoma on scrape preparations. Three cases from this category were diagnosed as papillary carcinoma on both frozen section and scrape preparations, leading to total thyroidectomy.

CONCLUSION

We conclude that intraoperative consultation is useful for thyroid lesions diagnosed as suspicious for papillary thyroid carcinoma on fine-needle aspiration and that ultrafast Papanicolaou-stained scrape preparations can increase the efficacy of thyroid frozen sections and obviate a second procedure for completion thyroidectomy.

Thyroid cytology and histology

Fine needle aspiration (FNA) is an economical procedure that allows prompt evaluation of a thyroidal mass. Careful attention to each step of the aspiration will allow good specimens to be obtained. The cytopathologist should obtain the aspirates or else should accompany the clinician performing the aspirations. Unsatisfactory specimens should constitute less than 5% of the total. Reliable diagnoses can be made of papillary carcinoma, medullary carcinoma, anaplastic carcinoma, chronic lymphocytic thyroiditis, benign cystic lesions and the usual colloid-rich adenomatoid nodules. The diagnosis of follicular neoplasms and some cellular adenomatoid nodules remains problematical. Therefore, some thyroid operations inevitably yield benign follicular lesions.

Fine-needle aspiration of the thyroid: rate and causes of cytohistopathologic discordance

Fine-needle aspiration (FNA) of the thyroid gland is a widely utilized, sensitive, specific, and cost-effective method for the evaluation of thyroid nodules. The purpose of this study was to evaluate the accuracy of thyroid FNA and causes of cytohistological discordance in our institution. Six hundred twenty-five thyroid FNAs obtained from 503 females (mean age, 54) and 122 males (mean age, 51) in whom histopathologic follow-up material was available for review, were analyzed. FNAs were classified as: nondiagnostic, negative, intermediate, and positive for malignancy, and the histopathologic material was categorized as benign or malignant. The review revealed 93% sensitivity and 96% specificity for the FNA diagnoses. The FNA results were diagnostic in 87%, indeterminate in 6%, and nondiagnostic in 7% of the cases. Cytohistologic correlation was achieved in 88% of the cases. The false-negative rate was 4% and the false-positive rate was 8%. The most common pitfalls for false-negative diagnoses consisted of suboptimal material and underdiagnosis of papillary carcinoma due to cystic degeneration. The most common pitfall for false-positive cases was overdiagnosis of follicular neoplasms. Our study confirmed that FNA of thyroid nodules can be performed with high sensitivity and specificity by experienced clinicians or pathologists. The application of strict specimen adequacy rules for FNA interpretation is likely to decrease the rate of false-negative and false-positive diagnoses.

Diagnosis of benign thyroid lesions: fine-needle aspiration and histopathologic correlation

Fine-needle aspiration is now accepted as the initial procedure for diagnosing a thyroid nodule. General pathologists inevitably will be asked to interpret aspirates as this diagnostic tool continues to be more widely used. This procedure is relatively inexpensive, is safe, and nearly always provides information useful in deciding how to manage the patient. We emphasize the importance of obtaining a representative sample of good quality. This often occurs when the "interventional pathologist" performs the aspirations, but there is no reason that another practitioner cannot become expert. Both histologic and cytologic features are reviewed from normal thyroid tissue, autoimmune thyroiditis, adenomatoid nodules, and follicular neoplasms. We encourage the use of clear, simple, and uniform terminology to facilitate communication.

Fine-needle aspiration of thyroid nodules: correlation between cytology and histology and evaluation of discrepant cases

BACKGROUND

The purpose of this study was to evaluate the results of thyroid fine-needle aspiration (FNA) and to determine the reasons for the discrepancies between the cytologic and histologic diagnoses.

METHODS

The authors evaluated the cytologic and histologic results of 133 FNAs obtained from 92 patients who underwent subsequent thyroidectomies.

RESULTS

The initial cytologic results were indeterminate in 39 of 133 cases (29%) because a neoplasm could not be ruled out. These cases corresponded histologically to 9 adenomatoid nodules (ANs), 14 follicular adenomas (FAs), and 16 malignant thyroid neoplasms. The reported FNA diagnoses of the remaining 94 cases (71%) were 48 ANs, 19 follicular neoplasms (FNs), 21 papillary carcinomas (PCs), and 6 cases of Hashimoto's thyroiditis (HT). Correlation of cytology and histology showed that 69 of 94 FNA results (73%) correlated with the histologic diagnoses, whereas 25 (27%) were discrepant. The discrepancies resulted from cytodiagnostic errors in 13 cases (52%), suboptimal smears in 11 (44%), and an FNA sampling error in 1 (4%). The false-negative rate of FNA was 19% and the false-positive rate was 6%.

CONCLUSIONS

Diagnostic pitfalls and indeterminate FNA diagnoses were predominantly due to overlapping cytologic criteria between ANs, FNs, and follicular variants of PCs. Rendering a definite diagnosis on suboptimal FNA samples is also a significant source of pitfalls.

Papillary tissue fragments as a diagnostic pitfall in fine-needle aspirations of thyroid nodules

Fine-needle aspirates of three thyroid nodules displayed hypercellularity and papillary tissue fragments that suggested neoplasms. Neither microfollicles (either empty or with inspissated colloid) nor the characteristic nuclei of papillary carcinoma were evident. Surgical specimens contained adenomatoid nodules with focal papillary hyperplasia. These cases demonstrate that no single cytologic feature should be used independently in the cytologic diagnosis of thyroid lesions. Tumor cellularity and papillary tissue fragments should not be equated with neoplasia per se; all cytomorphologic features should be evaluated.

Fine-needle aspiration of thyroid lesions in 57 pregnant and postpartum women

Palpable thyroid nodules are common in women. The thyroid gland may enlarge in response to hyperemia, relative iodine depletion, and slight stimulation by beta Human Chorionic Gonadotrophin (HCG) during pregnancy. The presence of goiter or a discrete nodule requires investigation. Fine-needle aspiration (FNA), a reliable diagnostic tool, can be safely used during pregnancy. The tenet that a "histologic hyperplasia" accompanies the physiologic hyperplasia of pregnancy may hamper FNA interpretation. We reviewed 97 (10 previous, 46 pregnant, 13 postpartum, 1 spontaneous abortion, and 27 follow-up) aspirates of thyroid nodules from 57 patients. Cytologic diagnoses were divided into five categories: 31 benign, 7 cellular adenomatoid nodules, 5 suspicious for papillary carcinoma, 12 papillary carcinomas, and 2 follicular neoplasms. There were an unanticipated number of carcinomas. Lesions present before pregnancy did not show "progression" or significant change. No characteristic features ascribable to pregnancy were identified. Standard diagnostic criteria may be used in the evaluation of FNA of thyroid nodules from pregnant patients.

Fine-Needle Aspiration in the Evaluation of Thyroid Neoplasms

Fine-needle aspiration (FNA) is a safe, rapid, and accurate diagnostic tool. Although it continues to gain acceptance, the pace is slow. Probably, if more pathologists master the basics (i.e., learn how to obtain a good sample), this simple technique could be utilized to its fullest advantage. If the sample is not adequate or representative of the lesion, the diagnosis will not be correct. Based on personal experience, we believe that suction should be minimal when obtaining thyroid aspirates. Cytologic diagnostic criteria for the most common neoplasms of the thyroid gland are provided.

Fine-needle aspiration and the diagnosis of thyroid cancer

Fine-needle aspiration is a low-cost diagnostic tool, the principal value of which is to determine which patients should undergo surgery. The technique is deceptively simple. Team work and close cooperation among endocrinologists, surgeons, and pathologists are essential for success. Cytologic criteria for diagnosis of the most frequent malignancies found in thyroid aspirates have been provided.