Follicular variant of papillary carcinoma: cytologic findings on FNAB samples-experience with 16 cases

Between January 1, 1992 and December 31, 1997, a cytopathological diagnosis of follicular variant of papillary thyroid carcinoma (FVPC) was made on a series of 16 out of 18 patients with palpable nodules who underwent fine-needle aspiration biopsy (FNAB) in our Department. The results of aspiration biopsy were followed by histopathological examination of the surgically excised tissues. There were three false-negative aspirations (16.6%), of which two were probably bound to fine-needle sampling and one due to a mixture of benign and malignant cells which had originally gone unrecognized. The accuracy of the cytopathologic diagnosis in this variant was 88.8%. An analysis of the diagnostic cytopathological criteria was performed, which demonstrated the importance of both architectural features (monolayered and branching sheets, microacinar structures, and their combinations) and nuclear features (presence of nuclear grooves). Background -bound features were mainly represented by dense, nonfilamentous colloid. The cytopathologic findings in FVPC were compared to those found in a series of 10 usual papillary carcinomas (UPC) and 10 follicular neoplasms (FN). These latter had originally been diagnosed by FNAB and were subsequently classified histologically as follicular adenoma (n = 6), follicular carcinoma (n = 3), or adenomatoid colloid nodule (n = 1). Statistical evaluation was performed on the cytopathological findings in the three classes of lesions (FVPC, UPC, and FN) as to their presence and relative frequency or absence by using a nonparametric one-way ANOVA (Kruskall-Wallis) and, where necessary, a Mann-Whitney U test. Papillary cellular fragments and multinucleated giant cells (P < 0.005), nonfilamentous dense colloid, squamoid cells, and syncytia were significantly more represented in UPC than in FVPC (P < 0.05), while histiocytes were significantly more frequent in FVPC (P < 0.005). Other nuclear and/or background features were significant only in the distinction between papillary carcinomas as a group and FN. The cytological differential diagnosis of the FVPC is briefly discussed with relevance to the possible pitfalls caused by its peculiar cyto- and histomorphology.     

Concomitant papillary thyroid carcinoma and Hashimoto's thyroiditis

An association between papillary thyroid carcinoma (PTC) and Hashimoto's thyroiditis (HT) is well recognized. Both entities may often display overlapping morphologic features. The aim of this study was to evaluate the accuracy of fine needle aspiration (FNA) of concomitant PTC and HT. Twenty nine thyroid FNAs with a diagnosis of concomitant PTC and HT on follow-up surgical material were retrospectively reviewed (11% of all HT cases diagnosed in the same period of time). The cytologic specimens were evaluated for the presence of diagnostic features of PTC and HT. In 16 of 29 cases, the diagnosis of PTC was made or suggested; however, only in 3 cases were both entities recognized on the FNA material. The review of the remaining cases (13 cases) showed diagnostic features of PTC in 2 cases (interpretation errors), some features of PTC in 8 cases (insufficient diagnostic features), features of only HT in 2 cases, and 1 case was acellular (sampling errors). Originally, 10 cases with features of PTC were diagnosed as either follicular neoplasm or colloid nodule with or without HT. Histologically, 1 of 13 cases was a cystic variant and 7 of 13 cases were follicular variants of papillary carcinoma. It is important to be aware of the coexistence of PTC and HT. Deliberate search for evidences of PTC in every case of HT may be necessary to improve diagnostic accuracy of the FNA. However, the cytologic diagnosis of follicular variant of PTC coexisting with HT can be challenging. The sampling error may also cause false negative results.     

Follicular neoplasm of the thyroid—vanishing cytologic diagnosis?

The significance of making a diagnosis of follicular neoplasm on fine needle aspiration (FNA) biopsy remains a controversial issue, considering that the diagnosis of follicular carcinoma is based on histological criteria and the significantly decreasing incidence of follicular carcinoma in the general population. On FNA the main differential diagnoses of follicular neoplasm includes follicular variant of papillary carcinoma (FVPC), follicular adenoma, follicular carcinoma and benign solitary nodule occurring in a goiter. Several studies have looked at immunohistochemical and molecular markers to distinguish benign from malignant lesions but none of them have proved to be infallible. Although, FVPC is a distinct entity from the follicular neoplasm group, it is not always possible to separate it from the other follicular lesions because of overlapping cytologic features and often-sporadic presence of nuclear features, follicular variant of papillary carcinoma remains the main pitfall in a diagnosis of follicular neoplasm. Since a significant number of cases that are malignant on follow-up are usually FVPC, consequently, follicular neoplasm is an essential diagnostic consideration on FNA. In addition, follicular carcinoma, despite a decreasing incidence continues to be a real entity. Therefore, it is essential that follicular neoplasm continue to be part of our diagnostic repertoire.     

Predictive Factors of Malignancy in Thyroid Nodules with a Cytological Diagnosis of Follicular Neoplasm

In cases of follicular neoplasm identified by thyroid fine-needle aspiration (FNA), surgery is required to achieve a precise diagnosis. We investigated potential clinical factors for the preoperative prediction of malignancy in thyroid nodules with a cytological diagnosis of follicular neoplasm. We retrospectively reviewed the data of 97 patients who were diagnosed with follicular neoplasm by FNA and had undergone surgery at the Korea Cancer Center Hospital between April 2010 and April 2012. Age, sex, laboratory data (such as thyroid-stimulating hormone, free T4, thyroglobulin (Tg), and Tg antibody), and ultrasonographic findings were reviewed from the electronic medical records. Of 97 patients, 50 (51.5 %) were diagnosed with benign nodules, 16 (16.5 %) with follicular thyroid carcinoma (FTC), and 31 (32.0 %) with papillary thyroid carcinoma (PTC). In comparison with the features of benign nodules, FTC presented with a large nodule size, high serum Tg level, isoechogenicity, calcifications, and peripheral halo, whereas PTC exhibited traits similar to those of benign nodules, except for high serum Tg level and the presence of calcifications on ultrasonography. Therefore, a high serum Tg level (≥75 ng/mL) and calcification were the only significant predictive factors for malignancy in case of follicular neoplasm (p?<?0.01). Serum Tg levels and the presence of calcification on ultrasonography are important clinical features to predict malignancy in thyroid nodules with cytological diagnosis of follicular neoplasm.     

Comparison of Consecutive Results from Fine Needle Aspiration and Core Needle Biopsy in Thyroid Nodules

There are papers suggesting the complementary role of core needle biopsy (CNB) in the diagnosis of thyroid nodules. By comparing the result of CNB and fine needle aspiration (FNA) cytology performed in consecutive cases of thyroid nodules, the role of CNB was evaluated. Retrospective reviews of 2131 FNA and 275 CNB which were performed as first-line biopsy for 2406 thyroid nodules in 2187 patients were performed. The ultrasound (US) feature of thyroid nodule was classified following the risk of malignancy suggested by American Thyroid Association (ATA) guideline. Rate of unsatisfactory and cellular atypia could be decreased significantly by first-line CNB in all US group, and the nodules with highly suspicious feature showed significant decrease in inconclusive result by first-line CNB. However, increased rates of architectural and follicular neoplasm (FN) were identified in CNB group especially in intermediate and low suspicious nodules, and the first-line CNB could not decrease the inconclusive result in these US groups. The diagnostic rate of neoplasm diagnosed by surgery following the result of architectural atypia or FN was not different between FNA and CNB even with significantly higher rate in CNB group. Furthermore, the sensitivity for follicular neoplasm (21.2 vs. 61.9%) was significantly higher in CNB group. The CNB can be considered in nodules with highly suspicious feature with advantage of significantly lower inconclusive diagnostic rate than FNA group. However, significantly increased diagnosis of architectural atypia or FN in other nodules by CNB is recognized and should be evaluated in future to understand the meaning.     

Follicular adenoma with squamous metaplasia and cystic change: report of a case with fine needle aspiration cytological and histological features

Squamous metaplasia (SM) of thyroid follicular epithelium is known to occur in a variety of non-neoplastic lesions as well in thyroid neoplasms, notably papillary carcinoma (PC). In follicular thyroid tumors, on the other hand, SM is very rare. This case describes cytological and pathological findings in a follicular adenoma (FA) that presented as a cystic lesion with extensive SM. The fine needle aspiration (FNA) cytology sample in this case yielded only necrotic material from the cystic area and squamous cells, which being mostly of immature type, were not recognised as squamous in the cytological smears. The needle missed the solid (neoplastic) component of the lesion and on the whole the cytological picture was considered to be equivocal. FA can now be added to the spectrum of thyroid lesions that can show SM. Awareness of this will enable cytopathologists to consider non-papillary lesions in the differential diagnosis of thyroid nodules that yield squamous cells.     

Fine-needle aspiration cytology of the thyroid: ten years experience in a community teaching hospital

We present our experience of fine-needle aspiration (FNA) cytology of the thyroid in a community hospital setting and discuss the cancer probability of the indeterminate FNA results. There were 1,621 FNAs, 401 of which have follow-up thyroidectomies during a 10-yr period. The initial FNA diagnoses of these 401 cases were benign non-neoplastic (BNN) 159, malignant 34, atypical 33, suspicious 19, follicular neoplasm (FN) 88, follicular lesion (FL) 51, and inadequate 17. There were no false-positive cases. Cancer was found in 11 cases diagnosed as BNN (7%), 6 cases were due to sampling errors (incidental microcarcinomas), and 5 cases were due to failure to identify focal atypia in the smears of a follicular variant of papillary carcinoma. The false-negative rate was 3%, with the exclusion of cases of incidental microcarcinomas. Among the indeterminate FNA results, the follow-up operations revealed malignant tumors in 16 of 33 (48%) cases of atypical, 13 of 19 (68%) cases of suspicious, 29 of 88 (33%) cases of FN, and 7 of 51 (14%) cases of FL. Malignant tumors were also found in 2 of 17 (12%) of inadequate specimens with follow-up. When compared to the cancer rate (3%) for FNA diagnosis of BNN, the likelihood of finding cancer in the thyroidectomy is 5 times more for a FL, 11 times more for a FN, 16 times more for atypical, and 23 times more for suspicious. The sensitivity and specificity are 87 and 100%, respectively.     

“Cellular adenomatoid nodules” of the thyroid: Review of 219 fine-needle aspirates

We reviewed 219 consecutive thyroid aspirates previously diagnosed as “cellular adenomatoid nodule.” applying the criteria presented in this paper and reclassifying them as 146 adenomatoid nodules (AN), 31 cellular adenomatoid nodules (CELL-AN), 29 cellular adenomatoid nodules vs. follicular neoplasms (CELL-AN vs. FN), 5 follicular neoplasms (FN), 2 FN of oxyphilic cell type, 4 papillary carcinomas, and 2 chronic lymphocytic (Hashimoto's) thyroiditis. Of the 146 adenomatoid nodules, 14 occurred in multinodular goiters on histologic examination. Of the 31 CELL-AN, five had surgery: two were follicular adenomas, one was papillary carcinoma, and two were multinodular goiters. Of the 29 CELL-AN vs. FN, 11 had surgery: six were follicular adenomas, two were follicular carcinomas, two were multinodular goiters, and one was Hashimoto's thyroiditis. Surgery on four FN showed follicular adenomas (a fifth patient was lost to follow-up). Of the two FN of oxyphilic cell type, one was a multinodular goiter and the other a follicular adenoma with oxyphilic cells. Three of the four papillary carcinomas were confirmed histologically (one patient was lost to follow-up). Of the two cases showing Hashimoto's thyroiditis, one was diagnosed as FN on repeat aspiration and follicular carcinoma at surgery. After review, we identified 40 patients at higher risk of harboring a neoplasm and 31 with cellular adenomatoid nodules. Twenty-five underwent surgery with the above results. In the classification of follicular lesions of the thyroid by FNA, adherence to strict cytologic criteria helps identify those patients who will benefit most from surgery.     

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.     

The fine-needle aspiration appearance of the follicular variant of thyroid papillary carcinoma: A report of three cases

The follicular variant of thyroid papillary carcinoma (FVTPC) is an uncommon neoplasm with the architectural features of a follicular lesion and the nuclear characteristics of a papillary carcinoma. The fine-needle aspiration (FNA) appearance is underreported in the literature. Three cases of histologically confirmed FVTPC that were aspirated prior to surgery are presented. Although the cytological features were suspicious or confirmatory of a low-grade thyroid carcinoma, they did not convey a specific diagnosis of the FVTPC. We suggest that this variant is recognizable as a neoplasm requiring surgical excision on FNA, but that the cytological appearance does not allow its specific diagnosis.     

Adenomatoid nodules are the main cause for discrepant histology in 234 thyroid fine-needle aspirates reported as follicular neoplasm

According to several large studies, the surgical pathologist renders a non-neoplastic diagnosis in ～20-40% of thyroid fine-needle aspiration (FNA) cases reported as follicular neoplasm. This study analyzes the cause of this poor correlation between cytology and histology. Cases consisting of oncocytic (Hurthle) cells were excluded from study. During the study period from January 1996 to April 2010, histologic follow-up was available for 234 of 670 cases (34.9%) reported as follicular neoplasm on ultrasound-guided thyroid FNA. Sonographic and Doppler data were available in all cases and included nodule location, size, echogenicity, and vascularity. Of the 234 aspirates with follow-up, surgical pathology reported 130 cases (55.6%) of follicular adenoma, 15 cases (6.4%) of follicular carcinoma, 14 cases (6.1%) of follicular variant of papillary carcinoma, and 75 cases (32.3%) of nodular goiter. Recuts of those index nodules reported as nodular goiter were examined independently by two pathologists using the 2× objective lens. Adenomatoid nodule was defined as an insufficiently encapsulated "blue" nodule of increased nuclear density when compared with the surrounding thyroid. Of the 75 cases reported as nodular goiter, 60 index nodules (80%) fulfilled the described criteria for adenomatoid nodule, while 15 did not. In conclusion, adenomatoid nodules are the main cause of poor histologic correlation with follicular neoplasm reported by FNA. If "increased nuclear density at scanning magnification" were adopted by surgical pathologists as the major diagnostic criterion for follicular adenoma rather than encapsulation, noncorrelated cases would be reduced from 32 to 6.4%.     

Use and abuse of frozen section in the diagnosis of follicular thyroid lesions

The role of intraoperative frozen section in certain organ systems such as the thyroid continues to be problematic. In many cases, diagnoses are deferred or nonhelpful—“follicular lesion.” In the modern era, the widespread use of preoperative aspiration biopsy has allowed for more careful selection of patients who undergo thyroid surgery. In many cases, the fine-needle-aspiration (FNA) biopsy diagnosis can be definitive or can guide the specific surgical procedure. The literature supports our approach, which is summarized as follows: Intraoperative consultation is not needed on the intrathyroidal nodule if a preoperative FNA was definitive for papillary carcinoma. Frozen section is of no value in the intraoperative diagnosis of lesions diagnosed on FNA as “follicular neoplasm” or “Hürthle cell neoplasm” because the characterization of these lesions requires detailed analysis of the tumor capsule for the demonstration of capsular and/or vascular invasion—an analysis that is not practical in the intraoperative setting. Finally, intraoperative consultation including frozen section and intraoperative cytologic examination is most useful in those cases that are diagnosed as suspicious for papillary carcinoma by FNA, because the assessment of nuclear features needed for the definitive diagnosis is possible with intraoperative techniques in a significant number of cases.     

Cytology of the thyroid gland: Pitfalls in aspiration of the fibrotic nodule

Fibrotic changes can be found in a variety of pathologic processes that affect the thyroid gland, and yet fine-needle aspiration (FNA) correlation of these lesions is not well-known. Cytologic findings are described from three different lesions, all with extensive fibrosis, that occurred in thyroid gland FNA. In each case, fibrotic changes resulted in cytologic changes potentially representing pitfalls in aspiration diagnosis. FNA revealed, solely or predominantly, fibroblasts in 2 patients whose subsequent thyroidectomies disclosed diffusely sclerotic papillary carcinoma and multinodular goiter. In the third case, an initially suspicious FNA was followed by multiple unsuccessful attempts at a second FNA. At thyroidectomy, a follicular adenoma with post-FNA fibrosis and infarction was identified. The differential diagnoses in thyroid FNA of fibrotic nodules can be broad, and this is discussed. Awareness of potential pitfalls may improve diagnostic accuracy. Diagn Cytopathol 1996;14:362–366. © 1996 Wiley-Liss, Inc.     

细胞角蛋白19、galectin-3、HBME-1在甲状腺病变上的表达及鉴别诊断意义

目的 研究细胞角蛋白(CK)19、galectin(Gal)-3、HBME-1在甲状腺不同病变表达的特点及鉴别诊断中的应用价值。方法 应用免疫组织化学EnVision法检测了21例结节性甲状腺肿(结甲)、14例毒性甲状腺肿(甲亢)、15例甲状腺滤泡性腺瘤(腺瘤)、13例滤泡性癌、13例滤泡型乳头状癌及48例经典型乳头状癌中单克隆抗体CK19、Gal-3、HBME-1的表达。结果 甲状腺病变中3种标记表达均位于细胞质;CK19、Gal-3、HBME-1的表达在甲状腺良性病变(结甲、甲亢、腺瘤)大多为弱阳性或阴性,而滤泡性癌阳性明显增加、乳头状癌(滤泡型及经典型)大多为中、强阳性,3种标记在甲状腺不同病变的阳性表达率结甲为52．4％(11／21)、9．5％(2／21)、19．0％(4／21),甲亢为50．0％(7／14)、7．1％(1／14)、7．1％(1／14),腺瘤为60％(9／15)、13．3％(2／15)、13．3％(2／15),滤泡性癌为76．9％(10／13)、61．5％(8／13)、53．8％(7／13),滤泡型乳头状癌为：100％(13／13)、84．6％(11／13)、92．3％(12／13),经典型乳头状癌为100％(48／48)、93．8％(45／48)、95．8％(46／48);在甲状腺良性病变(结甲、甲亢、腺瘤)与恶性病变(滤泡性癌、乳头状癌)间3种标记差异均有显著性(P均=0．000);同时3种标记在滤泡样病变即腺瘤、滤泡性癌和滤泡型乳头状癌间亦有显著差异(CK19：P=0．038,Gal-3：P=0．001,HBME-1：P=0．000)。结甲有9例,甲亢有7例,腺瘤有6例3种标记均不表达,滤泡性癌仅有1例,而乳头状癌(滤泡型及经典型)没有病例3种标记均不表达,同一病例有2种以上阳性表达在结甲、甲亢、腺瘤、滤泡性癌、滤泡型乳头状癌和经典型乳头状癌中分别为14．2％(3／21)、21．4％(3／14)、20．0％(3／15)、69．2％(9／13)、92．3％(12／13)、100．0%(48／48),在甲状腺良性病变与恶性病变间以及滤泡样病变间差异亦有显著性(P=0．000)。结论 CK19、Gal-3、HBME-1的检测尤其是联合检测对甲状腺病变的诊断、鉴别诊断具有较高的实用价值。     

Peroxisome proliferator-activated receptor gamma expression in follicular-patterned thyroid lesions. Caveats for the use of immunohistochemical studies

To determine its usefulness as a specific diagnostic marker for follicular carcinomas (FCs) vs other follicular-patterned thyroid lesions and possible application to fine-needle aspiration specimens, we immunohistochemically studied peroxisome proliferator-activated receptor gamma (PPAR gamma) expression in histologic sections (FC, 13 cases; follicular adenoma [FA], 11; follicular variant of papillary carcinoma [FVPC], 9) and surrounding thyroid tissue by using a PPAR gamma monoclonal antibody. Positivity (detected by nuclear staining) was scored as absent, weak, moderate, or strong. When only moderate or strong nuclear staining was considered positive, 9 FCs (69%), 3 FAs (27%), and 2 FVPCs (22%) demonstrated positive nuclear immunoreactivity. The sensitivity and specificity of immunohistochemical detection of PPAR gamma expression in FCs were 69% and 75%, respectively. In nonlesional surrounding tissue, moderate to strong positive staining was seen in focal areas of chronic lymphocytic thyroiditis in 6 of 33 cases (FC, 2; FA, 3; FVPC, 1); diffuse moderate staining was detected in surrounding tissue in the absence of lymphocytic thyroiditis in 4 cases (12%; FC, 3; FA, 1). Staining in the follicular-patterned lesions and surrounding nonlesional thyroid was specific with peptide blocking experiments. PPAR gamma expression is not a specific marker for FCs, and its detection in nonlesional thyroid tissue suggests limited usefulness as a diagnostic marker for follicular-patterned lesions in general.     

Suspicious sonographic and cytological findings in patients with subacute thyroiditis: Two case reports

We here report on two cases of suspicious cytological findings upon ultrasound (US)‐guided fine‐needle aspiration (US‐FNA) in patients with subacute thyroiditis (SAT). A 46‐year‐old woman who underwent US‐FNA for a suspicious thyroid nodule in the right lobe at a local clinic was referred to our hospital for surgical treatment. Based on the cytology results, total thyroidectomy was performed. The histopathology findings confirmed the presence of SAT in the right lobe and absence of thyroid malignancy. A 40‐year‐old woman with a thyroid nodule in the left lobe with suspicious cytological findings upon US‐FNA was referred to our hospital for surgical treatment. However, neck US revealed typical sonographic findings of SAT. On follow‐up US 3 months later, near complete disappearance of the typical sonographic findings of SAT was observed, while a hypoechoic solid thyroid nodule in the left upper lobe was clearly visualized. Accordingly, US‐FNA was performed for the hypoechoic thyroid nodule. Papillary thyroid carcinoma was suspected on the basis of the cytology findings; histopathologically, SAT was confirmed in both thyroid lobes and a papillary thyroid carcinoma was confirmed in the left lobe. Diagn. Cytopathol. 2015;43:399–402. © 2014 Wiley Periodicals, Inc.     

Mixed medullary-follicular carcinoma of the thyroid: diagnostic dilemmas in fine-needle aspiration cytology

Mixed medullary-follicular carcinoma (MMFC) of thyroid is an extremely rare tumor, characterized by coexistence of morphological and immunohistochemical features of both medullary carcinoma and follicular (or papillary) carcinoma. We herein present fine needle aspiration (FNA) findings of a histology-confirmed MMFC along with a review of literature. The patient was a 64-year-old woman who had a history of Hashimoto's thyroiditis and presented with enlargement of preexisting right thyroid nodule. An US-guided FNA of the thyroid nodule was performed and conventional smears were prepared. A cytologic diagnosis of "positive for malignancy, consistent with medullary thyroid carcinoma (MTC)" was rendered based on the presence of features characteristic for MTC, and the absence of components of follicular neoplasm (adenoma and carcinoma) or papillary carcinoma. However, microscopic examination of the follow-up total thyroidectomy specimen with the aid of immunocytochemical study detected minor portion of follicular carcinoma in addition to MTC. A histologic diagnosis of MMFC was then established. While specific identification of MMFC by FNA may be difficult, it should be emphasized that adequate sampling in conjunction with the proper immunostaining panel could have highlighted the different aspects of the mixed tumor.     

Correlation of fine needle aspiration cytology and frozen section biopsies in the diagnosis of thyroid nodules.

AIMS: To evaluate the correlation of fine needle aspiration (FNA) cytology and frozen section biopsy in the diagnosis of thyroid nodules. METHODS: The medical records of 662 patients who underwent FNA cytology of the thyroid and thyroid surgery were analysed. Frozen section biopsies were taken from 586 of the 662 patients. The diagnostic correlations of FNA cytology, frozen section, and both FNA cytology and frozen section with definitive histological assessment were evaluated. RESULTS: Among the 662 patients who received FNA cytology, there were 356 cases (53.8%) diagnosed as benign, 114 cases (17.2%) as malignant, 148 cases (22.4%) as indeterminate, and 44 cases (6.6%) as unsatisfactory. The positive predictive value for the detection of malignancy by FNA cytology was 92.1% and the negative predictive value was 95.2%. The incidence of malignancy in the indeterminate cytological diagnosis was 23%. The diagnosis from frozen sections was benign in 445 cases (75.9%), malignant in 134 cases (22.9%), and deferred in 7 cases (1.2%). By frozen section, the positive and negative predictive values were 97% and 95.5%, respectively. Diagnostic accuracy up to 98% was achieved when FNA cytology and frozen section diagnoses were in agreement. No false positives were observed when FNA cytology and frozen sections were both positive for malignancy. When FNA cytology and frozen section diagnoses were discordant, frozen section showed a higher accuracy (78.9%) than FNA cytology (21.1%). In the face of an indeterminate or unsatisfactory cytological diagnosis, the diagnostic accuracy of frozen sections reached 92.6%. CONCLUSIONS: The results confirm that FNA cytology is a useful tool in the initial evaluation of thyroid nodules. Intraoperative frozen section is a valuable procedure to confirm the cytological diagnosis and identify malignancy in patients with indeterminate or unsatisfactory cytological diagnosis. With reliance on frozen sections as an intraoperative guide of thyroid surgery, the possibility of unnecessary extensive surgery and the need for the second operation are considerably lower.     

Large-needle aspiration biopsy for the preoperative selection of palpable thyroid nodules diagnosed by fine-needle aspiration as a microfollicular nodule or suspected cancer

The palpable thyroid nodules with a fine-needle aspiration (FNA) diagnosis of microfollicular nodule or suspected cancer usually are excised; however, most of them are proved benign by postoperative histologic examination. We reviewed the clinical and pathologic data for patients with thyroid nodules with an FNA diagnosis of microfollicular nodule or suspected cancer; nodules also were examined by large-needle aspiration biopsy (LNAB) to assess whether the distinction achieved by LNAB into pure microfollicular or mixed microfollicular-macrofollicular nodules could be used preoperatively to better predict malignancy. One hundred fourteen nodules of this type were excised. The prevalence of cancer was 22% (14/63) among the microfollicular and 4% (2/51) among the microfollicular-macrofollicular nodules at LNAB. These data indicate that histologic examination of the LNAB specimen can be used for preoperative selection of thyroid nodules diagnosed by FNA as a microfollicular nodule or suspected cancer.