An alternate model of thyroid cytology: practical not perfect

A sample of 384 thyroid cytology specimens prepared by cytospin over a 2.5-year period was classified by original report into inadequate, non-neoplastic and suspicious of neoplasia or worse. This was then compared with subsequent histology. The resulting data showed an inadequacy rate of 33%, a sensitivity of 55%, a specificity of 59%, a positive predictive value of 64% and a negative predictive value of 93%. On review of the cytology, in knowledge of the subsequent histology, the maximum achievable results were determined to have a positive predictive value of 79% and a negative predictive value of 97%. No clinically significant adverse event was detected.     

A morphometric analysis of cytological features of tall cell variant and classical papillary carcinoma of the thyroid

In order to assess whether morphometric parameters could be of value in distinguishing between tall cell variant and classical pattern of thyroid papillary carcinoma, the fine needle aspiration cytology (FNAC) samples of 14 cases were analysed using Arcimage 5 software on an Acorn computer. Histological examination of the specimens allowe classification of nine of them as classical pattern and the remaining five as tall cell variants. The nuclear diameter (NDD) and standard deviation distribution (NDSDD), th nuclear area (NAD) and standard deviation distribution (NASDD), and the nuclear/cytoplasmic ratio (NCR) were assessed on May-Grunwald-Giemsa stained smears. Statistical analysis was performed by use of one-way analysis of variance (ANOVA) of the two groups as identified by histology. Whilst NDD (P = 0.007), NAD (P = 0.015) and NADSD (P = 0.026) all appeared statistically significant, NDSD (P = 0.06) and NCR (P = 0.71) were not. The cytological diagnosis of papillary carcinoma is established and reproducible, but morphometric data on the thyroid have so far focused on the differential diagnosis between benign and malignant nodules. The choice of simple morphometric parameters appears to be helpful in the preoperative distinction between the classical pattern and tall cell variant of papillary carcinoma.     

Fine needle aspiration cytology of the thyroid: a comparison of 5469 cytological and final histological diagnoses

OBJECTIVE: We evaluated the efficacy of fine needle aspiration cytology (FNAC) of the thyroid in a series of 5469 lesions with histological control and studied the causes of, and the possibility of reducing the limitations of the method. METHODS: FNAC was always performed by a pathologist under the guidance of a clinician, using a 22-gauge needle. Generally two aspirations were carried out, and usually four slides were obtained for each nodule; they were then stained with May-Grünwald-Giemsa and with Papanicolaou. The cytological diagnoses were classified in four groups: inadequate, benign, suspicious and malignant. RESULTS: We obtained a complete sensitivity of 93.4%, a positive predictive value of malignancy of 98.6%, and a specificity of 74.9%. At histological control, the cytological diagnosis of Hurthle cell neoplasm corresponded to a significantly higher incidence of malignant neoplasms than the diagnosis of non-Hurthle cell follicular neoplasm (32.1% versus 15.5%). There were 66 false-negative findings, the main cause of diagnostic error (24 cases) being failure to recognize the follicular variant of papillary carcinoma. The number of inadequate FNACs was low (4.2%). CONCLUSION: Our study confirmed the great efficacy of thyroid FNAC. A cytological diagnosis of Hurthle cell neoplasm should be considered an indicator of high risk. Awareness that failure to recognize the follicular variant of papillary carcinoma was the main problem in the interpretation of thyroid FNAC should lead to a decrease of false-negative diagnoses. The inadequate rate was very low, as it was the pathologist personally who performed the needle aspiration.     

Fine needle aspiration cytology of thyroid nodules: how accurate is it and what are the causes of discrepant cases?

Fine-needle aspiration cytology (FNAC) is widely accepted as the most accurate, sensitive, specific and cost-effective diagnostic procedure in the assessment of thyroid nodules and helps to select people preoperatively for surgery. The purpose of this study was to evaluate the results of thyroid FNAC in our institution and to determine the reasons for discrepancies between the cytological and histological diagnosis. We evaluated the cytological and histological results of 254 FNACs obtained from 231 patients who underwent subsequent thyroid surgery. All of the material was blindly reviewed for quality control, by one experienced cytopathologist. All FNACs were carried out under ultrasound guidance. The cytological diagnosis was classified as benign, suspicious, malignant or unsatisfactory. The definitive histological study showed benign lesions in 195 of the 231 patients (84%). A benign diagnosis based on FNAC was correct in 105 of the 108 benign cases (97%). FNACs diagnosed as 'suspicious' resulted in a distribution of 49 benign (79%) and 13 malignant (21%) diagnoses. FNAC showed malignancy in 34 cases (13%) and in only one case did the final histology differ from cytology (correlation 97%). The percentage of FNACs that were inadequate for diagnosis was 20%. Review of cytological and histological slides did not lead to any change in the original diagnosis. Our study revealed a cytological-histological discrepancy (2%) in only 4 out of 231 cases over a period of 10 years, due to either a diagnostic or sampling error.     

Necrotic Debris In Thyroid Aspirates: A Feature of Follicular Carcinoma of the Thyroid

Fine needle aspirates from 44 follicular thyroid tumours (30 adenomas, 14 carcinomas) have been studied. All aspirates contained neoplastic cells in follicular and trabecular arrangements. The individual tumour cells showed varying degrees of anisonucleosis and nuclear pleomorphism. Colloid was scanty or absent from all smears. Granular or filamentous necrotic material was observed in both biopsies and smears from one moderately and two poorly differentiated follicular carcinomas, but in none of the adenomas. This suggests that necrotic debris may be a feature of follicular carcinoma of the thyroid.     

Thyroid fine needle aspiration cytology: a review of the National Cancer Institute state of the science symposium

L. J. Layfield, E. S. Cibas and Z. Baloch
Thyroid fine needle aspiration cytology: a review of the national cancer institute state of the science symposium In October 2007, the National Cancer Institute (NCI) of the United States sponsored a conference reviewing the state of the science of thyroid fine needle aspiration (FNA). Multiple issues were reviewed including pre‐FNA requirements, training specifications, criteria for the selection of patients to undergo FNA, diagnostic categories and criteria, ancillary testing and post‐FNA follow‐up and treatment options. A summation of conclusions covering three of these topics, followed by a question and answer session, was subsequently presented at the 35th European Congress of Cytology (ECC) in Lisbon, Portugal in September of 2009. At the ECC, the findings of the NCI committee proposals regarding the indications for FNA of thyroid nodules, diagnostic categories and criteria, and post‐FNA options for follow‐up and treatment were discussed. Herein we review the presentations given at that conference.     

Thyroid fine needle aspiration cytology processed by ThinPrep: an additional slide decreased the number of inadequate results

E. D. Rossi, F. Morassi, G. Santeusanio, G. F. Zannoni and G. Fadda
Thyroid fine needle aspiration cytology processed by ThinPrep: an additional slide decreased the number of inadequate results Background: Fine needle aspiration cytology is the most accurate tool for diagnosing thyroid nodules. Its accuracy is related to the rate of inadequate samples, which can be minimized with the adoption of on‐site assessment of the adequacy of the material. The introduction of liquid‐based cytology (LBC) in the thyroid does not allow checking on the adequacy of the cellularity. The possibility of making a second LBC slide for decreasing the number of non‐diagnostic cases is studied. Methods: Out of 553 cases diagnosed in a single institution from January to March 2005, 166 consecutive cases with an LBC slide reviewed by the same pathologist were evaluated. The cases were classified in a five‐tiered category system (Thy1 to 5 according to the British Thyroid Association guidelines) and all but two (with cystic degeneration) were processed by LBC and stained with Papanicolaou stain. The above‐mentioned categories are defined as follows: Thy1 inadequate or haemorrhagic, Thy2 non‐neoplastic lesion; Thy3 follicular lesion/suspected follicular neoplasm; Thy4 suspicious for malignancy; Thy5 diagnostic of malignancy. For each case the cytological diagnosis was made on the LBC slide and the adequacy of the cellularity for a conclusive diagnosis was assessed. Results: Of the 166 cases, 39 were non‐diagnostic (Thy1—inadequate), ten presented features of cystic degeneration (Thy1—haemorrhagic), 90 were benign (Thy2), 22 were diagnosed as a follicular lesion (Thy3), one as suspicious of malignancy (Thy4) and four as papillary carcinoma (Thy5). Thirty‐nine cases had a second LBC for achieving a definitive diagnosis with eventual re‐classification. Of these cases, 23 (61.5%) led to a conclusive diagnosis (18 Thy2, five Thy3) with a 18.5% decrease of the inadequacy rate. Conclusions: The making of an additional LBC slide helps in achieving a diagnosis in cases classified as non‐diagnostic on the first standard slide (52.1% recovery rate). This procedure is particularly helpful for meeting the adequacy criteria in benign and indeterminate lesions and could also be used for refining the diagnosis of suspicious for a malignant thyroid neoplasm.     

Fine needle aspiration cytology of primary lymphoma of the thyroid: a report of 17 cases.

Between 1980 and 1998, 4272 thyroid surgical specimens with a preoperative fine needle aspirate were sent to our Anatomical Pathology Department. Among these cases there were 17 primary thyroid lymphomas, which constituted 0.3% of all the thyroid lesions and 2.3% of the thyroid malignancies. Seven cases were diffuse large B-cell (DLBC) lymphomas and 10 were MALT lymphomas. Of the DLBC lymphomas six were correctly diagnosed by fine needle aspiration cytology (FNAC) and one was diagnosed as positive for malignancy, and among MALT lymphomas four were diagnosed as lymphoma, four as suspicious for lymphoma, and three as Hashimoto's thyroiditis (HT). Our data indicate that the diagnosis of primary thyroid lymphoma of high grade is easy, and immunocytochemistry (ICC) can confirm suspicious cases. The diagnosis of MALT lymphoma is more difficult; ICC can confirm suspicious cases, and false-negative results seem to be caused by sampling error, because HT usually coexists with MALT lymphoma.     

Fine needle aspiration cytology in non-neoplastic non-toxic recurrent nodular goitre

The aim of the study was to examine whether evaluation of anisokaryosis is helpful in the cytological diagnosis of focal lesions in non-toxic recurrent goitre (NRG) after thyroidectomy for non-malignant goitre. Karyometric analysis was performed in routine cytological smears obtained from 80 females: 40 with focal lesions in non-toxic primary goitre (NPG) and 40 with NRG (postoperative histopathological examination revealed nodular goitre in both groups in all cases). We found that the level of anisokaryosis was significantly (P<0.005) higher in NRG than in NPG. There were no significant differences between the two lesions, in cellular composition or thyroid follicular cell arrangement. Thus, isolated anisokaryosis, a feature of malignancy in patients without a prior thyroidectomy, has limited diagnostic value in recurrent goitre.     

Medullary Carcinoma of Thyroid: A Re-Evaluation of the Cytological Criteria of Diagnosis

We have reviewed the fine needle aspiration cytology appearances of a series of 31 consecutive and histologically confirmed medullary carcinomas of the thyroid. Despite the absence of a totally specific diagnostic feature, this retrospective re-evaluation indicates that a preoperative diagnosis of medullary carcinoma of the thyroid is possible in almost every case. The features occurring most commonly include a dispersed cell pattern in which round or spindle shaped cells with eccentric speckled nuclei were seen showing slight pleomorphism with inconspicuous nucleoli. In a third of cases fine red granularity was present in the cytoplasm in slides stained with Giemsa and by the Papanicolaou technique.     

Neural tumours of the neck presenting as thyroid nodules: a report of three cases

OBJECTIVES: Neural tumours of the neck may at times secondarily involve the thyroid and manifest clinically as thyroid nodules. On cytological evaluation these nodules may be confused with other spindle lesions of the thyroid. We report two cases of schwannoma and one case of a malignant peripheral nerve sheath tumour (MPNST) of the neck, which presented as thyroid nodules and evaluate the role of cytology in identifying these tumours. METHODS: The thyroid nodules in all the three cases were sampled by the non-aspiration technique using a 23-gauge needle. Both alcohol-fixed and air-dried smears were prepared and stained by the Papanicolaou and May-Grünwald-Giemsa stains. Cytology smears and histology sections from the resected specimens were reviewed, and the findings noted. RESULTS: Both the cases of schwannoma were correctly identified on cytology while the case of MPNST could only be typed as a spindle cell tumour. However, on cytology it was not possible to state whether the tumours were thyroidal or extrathyroidal in origin. CONCLUSIONS: Schwannomas of the neck are easily identifiable on cytology compared with MPNST. However, cytology alone is not helpful in identifying the origin of these tumours. As primary neural tumours of the thyroid are rare, the possibility of a soft tissue neural tumour extending into the thyroid should always be ruled out while evaluating these cases.     

Fine needle aspiration cytology of medullary carcinoma of the thyroid with a focus on rare variants: a review of 78 cases

S. Kaushal, V. K. Iyer, S. R. Mathur and R. Ray
Fine needle aspiration cytology of medullary carcinoma of the thyroid with a focus on rare variants: a review of 78 cases Background: The cytological features of variants of medullary carcinoma of the thyroid (MCT) are sparsely documented in the literature from case reports. Detailed cytomorphological analysis of MCT variants and features helping to distinguish them from usual MCT are presented here. Materials and methods: A total of 78 aspirates with a diagnosis of MCT over a period of 10 years were re‐evaluated. Cytomorphological details were reviewed and semiquantitatively analysed. Histology slides were reviewed in 36 cases. Results: Most aspirates showed classical features of dispersed polygonal or plasmacytoid cells with areas of spindling. In 54 aspirates, a definite cytological diagnosis of medullary carcinoma was made, which in 87.1% was based on cytomorphology alone and in 12.9% was based on immunocytochemistry for calcitonin. In 30.1% of aspirates from MCT, a guarded report of tumour was given in the absence of calcitonin immunocytochemistry. Of the 78 cases, nuclear grooves were seen in 5.1%, intranuclear cytoplasmic inclusions in 28.2%, cytoplasmic granularity in 23.1% and bizarre cells with abrupt anisocytosis in 85.9%. A follicular arrangement was seen in 14.1% and was more frequent in the follicular type (one case) and mixed follicular and medullary carcinoma (one case). Melanin production was seen in aspirates from two cases. One case of the giant cell type of MCT was seen, in which background cells showed large pleomorphic nuclei and numerous bizarre tumour giant cells, prompting a differential diagnosis with anaplastic carcinoma. One example each of the small cell type, paraganglioma‐like MCT and papillary MCT were seen. Conclusions: MCT has uniform cytological features in the majority of aspirates, including many of the histological variants. Searching for pigment in every aspirate of MCT may be rewarding. The giant cell type of MCT is rare and has to be differentiated from anaplastic carcinoma.     

Fine needle aspiration cytodiagnosis of anaplastic carcinoma and malignant haemangioendothelioma of the thyroid in an endemic goitre area

Between 1970 and 1987, 20,028 fine needle aspirates (FNA) of the thyroid have been examined in the Department of Pathology of the University of Innsbruck, Austria. During this period 92 cases of anaplastic carcinoma and 16 cases of malignant haemangioendothelioma (MHE) of the thyroid were diagnosed. Forty-three out of these 108 highly malignant tumours of the thyroid underwent FNA pre-operatively (39.1%). Thirty-seven FNA contained numerous cells of a highly malignant tumour. Five specimens (11.8%) contained only necrotic material and inflammatory cells. In one case of an anaplastic carcinoma no malignant cells could be demonstrated in FNA. We conclude that pre-operative FNA of highly malignant thyroid tumours may contribute substantially to subsequent clinical management.     

Management of thyroid cytological material,preanalytical procedures and bio‐banking

Thyroid nodules are common and are increasingly detected due to recent advances in imaging techniques. However, clinically relevant thyroid cancer is rare and the mortality from aggressive thyroid cancer remains constant. Fine needle aspiration cytology (FNAC) is a standard method for diagnosing thyroid malignancy and the discrimination of malignant nodules from goitre. As the examined nodules on thyroid FNAC are often small incidental findings, it is important to maintain a low rate of undetermined diagnoses requiring further clinical work up or surgery. The most important factors determining the accuracy of the cytological diagnosis and suitability for biobanking of thyroid FNACs are the quality of the sample and availability of adequate tissue for auxiliary studies. This article discusses technical aspects (preanalytics) of performing thyroid FNAC, including image guidance and rapid on‐site evaluation, sample collection methods (conventional slides, liquid‐based methods, cell blocks) and storage (bio‐banking). The spectrum of special studies (immunocytochemistry on direct slides or liquid‐based cytology, immunohistochemistry on cell blocks and molecular methods) required for improving the precision of the cytological diagnosis of the thyroid nodules is also discussed.