Posters. P17 Accuracy of fine needle aspiration cytology in diagnosis of thyroid swellings

Introduction Fine needle aspiration cytology is regarded as the gold standard investigation in diagnosis of thyroid swellings. Published data suggest an overall accuracy rate of 75% 1 in the detection of thyroid malignancy. The aim of this study was to determine the accuracy of FNA cytology in detection of thyroid malignancy in our surgical unit. Methods Between 1989–2002, 144 patients who underwent thyroid resection by single consultant surgeon and who had pre‐operative FNA were enrolled in this retrospective study. The pre‐operative FNA results were compared with definitive histological diagnosis following thyroid resection. Fine needle aspiration cytology was performed using aspirate and non‐aspirate techniques on each thyroid swelling. The cytological sample was assessed by a single cytopathologist and was classified as inadequate, non‐neoplastic, neoplastic, suspicious or indeterminate. The histology was classified as non‐neoplastic (benign) and neoplastic (malignant). Results Fine needle aspiration cytology analysis revealed 94 (13.88%) non‐neoplastic, six (65.27%) neoplastic and 20 (4.16%) suspicious aspirates. Twenty (13.88%) samples were inadequate and four (2.77%) samples were indeterminate. Histological analysis showed 118 (81.94%) benign, 26 (18.05%) malignant specimens. Fine needle aspiration cytology had a sensitivity, specificity and accuracy rate of 52.6%, 86.6% and 79.1%, respectively for diagnosing thyroid malignancy. Conclusion The results are comparable with the current published data and demonstrate that FNA cytology in our hands is accurate investigation for pre‐operative diagnosis for the detection of thyroid malignancy.     

Fine needle aspiration cytodiagnosis of clinically suspected tuberculosis in tissue enlargements

A retrospective study of the use of fine needle aspiration (FNA) cytology to confirm a clinical suspicion of tuberculosis in tissue enlargements was performed, using 70 cases. The criteria required to make an FNA cytodiagnosis of tuberculosis were reassessed, and the sensitivity and predictive value of cytology for diagnosing such aspirates was determined. All but 2 of the 70 aspirates contained adequate cellularity. The adequate samples were diagnosed as 40 cases of caseating tuberculosis, 11 cases of noncaseating tuberculosis and 17 cases of acute necrotizing granulomatous inflammation suspicious for tuberculosis. Subsequent histologic study verified the cytologic diagnosis in 27 of 27 biopsied caseating lesions, 4 of 7 biopsied noncaseating cases and 5 of 8 necrotizing cases. The six cases with a false-positive cytodiagnosis of tuberculosis were histologically diagnosed as one Lennert's lymphoma, two reactive lymph nodes and three necrotizing metastatic carcinomas. The sensitivity of FNA cytology for the diagnosis of tuberculosis was 100%, with the predictive value of a positive result being 88%. The findings in this study emphasize that all criteria for the diagnosis of tuberculosis in FNA samples must be utilized and that particular caution should be exercised in making a diagnosis of acute necrotizing tuberculosis.     

Phyllodes tumor of the breast. A cytohistologic study of 80 cases

OBJECTIVE: To study the cytologic features of phyllodes tumor (PT) of the breast and determine the accuracy of their subclassification in fine needle aspirates. STUDY DESIGN: Eighty cases of histologically diagnosed PT between 1982 and 1997 with a previous fine needle aspiration (FNA) were evaluated. The FNA smears of each case were reviewed without knowledge of the initial cytologic diagnosis and subclassified into benign, borderline or malignant PT. RESULTS: Benign PTs were characterized by a dimorphic mixture of stromal and epithelial cells. The stromal fragments showed mild to moderate cellularity with absent to minimal pleomorphism and no mitosis. There were occasional, if any, single stromal cells. Borderline PTs had stromal fragments with moderately cellular stroma exhibiting moderate pleomorphism. Two additional features were the presence of single stromal cells and an occasional mitosis in the stromal fragments/single cells. Aspirates from malignant PT were very cellular, with a high stromal/epithelial ratio and marked stromal cellularity. The stromal cells were highly pleomorphic, with frequent mitosis and atypical single stromal cells in the background. Fifty-seven of the 80 histologically documented cases (71.3%) were diagnosed as PT on FNA (40 benign, 10 borderline and 7 malignant). In 81% (46 of 57 PTs), good cytohistologic correlation (32 benign, 8 borderline and 6 malignant) was observed. In another eight cases, one grade differentiation between cytologic and histologic grade was observed. Six of the nine malignant PTs on histology were correctly subclassified on cytology. There were one false positive and two false negative cases. CONCLUSION: Cytologic diagnosis and grading of PT on FNA is possible. Special care should be undertaken in interpreting phyllodes fragments, cellularity of stroma, pleomorphism and mitosis. Single stromal cells are also important morphologic criteria for subclassification. Multiple-site aspiration is advisable to avoid diagnostic errors.     

Cytomorphology of lipomatous tumors of soft tissue

OBJECTIVE: To evaluate the cytomorphologic features of benign and malignant lipomatous tumors of soft tissue on fine needle aspirates (FNA) and determine if the variants of liposarcoma could be identified. STUDY DESIGN: FNA of histologically documented benign (51 cases) and malignant (39 cases) lipomatous tumors were reviewed. Twenty-six of the 51 FNA from lipomas and 34 of the 39 FNA from malignant lipomatous tumors were satisfactory for evaluation. RESULTS: FNA from 26 cases of lipomas were cellular, with lobulated, fibroadipose tissue. Thin and thick capillaries were seen in 92% and 65% of cases, though a chicken wire vascular pattern was seen in only 4 cases (15%). A cytodiagnosis of liposarcoma could be made in 23 cases (88%), and these could be further subtyped into well-differentiated (4 cases), myxoid (8), pleomorphic (4), round cell (3) and liposarcoma, ?type (4). Only 50% of the well-differentiated liposarcomas, 3 of the 10 pleomorphic liposarcomas and 8 of the 17 myxoid liposarcomas were diagnosed as such on FNA. Cytologic diagnosis of the remaining 9 cases of myxoid liposarcoma were pleomorphic liposarcoma (1); liposarcoma, ?type (3); malignant mesenchymal tumor (1); suspicious for malignancy (2); and benign (2). There were no false positives, but there were 3 false negative cases (1 well-differentiated and 2 myxoid liposarcoma). CONCLUSION: Lipomas can be diagnosed readily. Arborizing vessels can be seen in lipomas and should be interpreted with caution. Subclassification of liposarcomas on FNA is possible but not very reliable. Myxoid liposarcomas pose a problem, and aspirates from them can mimic a wide range of morphologic subtypes. The role of FNA in identification of variants of liposarcoma is limited.     

Morphologic and immunocytochemical evaluation of 220 fine needle aspirates of malignant lymphoma and lymphoid hyperplasia

A total of 220 fine needle aspiration (FNA) specimens from 212 patients with clinically suspected or previously histologically confirmed lymphoma were evaluated by cytology in conjunction with immunophenotyping analysis of the aspirate; the results were compared with the histologic diagnosis made on previous or current accessions of lymph node or extranodal tissue. Smears of the aspirates were stained with the Diff-Quik and Papanicolaou stains while immunoperoxidase staining using antibodies against kappa and lambda immunoglobulin light chains and Leu-4 was routinely performed on Cytospin preparations. Where indicated, additional marker studies (including T-200, Leu-1, Leu-2a, Leu-3a + 3b, Leu-M1, B1, Leu-12, IgM, CALLA and TdT) were performed. For the non-Hodgkin's lymphomas, specimens were classified by the cytologic characteristics of the neoplastic cells according to the International Working Formulation scheme. The combination of cytologic smears and immunoperoxidase studies resulted in a diagnosis of lymphoma in 173 cases (79%). The remaining aspirates were interpreted as suspicious for lymphoma (7%), benign (10%) or inadequate for diagnosis (4%). Of the 15 suspicious aspirates, 5 proved to be Hodgkin's disease and 2 to be T-cell lymphoma by subsequent biopsy. The cause of failure in the nine inadequate aspirates were necrosis (3 cases), sclerosis (2 cases) and faulty technique (4 cases). In the cases that had concurrent tissue biopsies, no false-positive diagnoses were rendered. These results indicate that FNA used in association with immunocytochemistry is a reliable tool for establishing the diagnosis and classification of the majority of cases of lymphoma. Optimal immunoglobulin light-chain ratios for defining monoclonality in FNA specimens of B-cell lymphomas are proposed.     

Flow cytometry as an accurate tool to complement fine needle aspiration cytology in the diagnosis of low grade malignant lymphomas

S. Schmid, M. Tinguely, P. Cione, H. Moch and B. Bode
Flow cytometry as an accurate tool to complement fine needle aspiration cytology in the diagnosis of low grade malignant lymphomas Objective: Diagnosis of low grade non‐Hodgkin B‐cell lymphomas on cytological material may be problematic and in the past frequently required lymph node excision. We analysed our experience of the value of flow cytometry (FC) as an additional tool for the diagnosis of lymphoproliferative processes in the setting of a university cytology division with a busy fine needle cytology service. Methods: Consecutive cytological specimens with FC over a period of 3 years were retrospectively analysed and correlated with histology and follow‐up if available. FC was performed with the following antibodies: CD3, CD4, CD8, CD2, CD7, CD19, CD5, CD10, CD23, lambda and kappa chains. Results: Of 299 probes (273 fine needle aspirations and 26 fluids from 285 patients), 179 cases (60%) were diagnosed as reactive, 91 cases (30%) as malignant or suspicious and 29 cases (10%) as inconclusive. The results of histological examination of the lymph nodes were available in 41 of 91 (45%) malignant or suspicious cases and in 13 of 179 (7%) reactive cytological diagnoses. Cytologically diagnosed malignancy was confirmed in all histologically examined cases. In 12 of 13 reactive cytological cases (92%), a benign process was diagnosed histologically. In 34 of 299 cases (11%) additional molecular investigations of B‐cell clonality or specific translocations were performed. The lymphomas most frequently diagnosed were follicular lymphoma and lymphocytic lymphoma, followed by mantle cell and marginal zone lymphomas. Correlation with histology showed a sensitivity of 98% and a specificity of 100% for cytology in our series. Conclusions: FC is an important additional tool in the cytological diagnosis of lymphoproliferative disorders. The combined approach has a high diagnostic value that allows a reliable subclassification of low grade B‐cell non‐Hodgkin lymphomas.     

Diagnosis of pancreatic carcinoma by fine needle aspiration cytology and computerized cytomorphometry

Eighty-one fine needle aspirations (FNAs) of pancreatic masses were performed between 1980 and 1988. Histologic or clinical follow-up was available for correlation with 78 aspirates. The FNA cytologic diagnosis of pancreatic carcinoma had a sensitivity of 79% and a specificity of 91%. Fifteen of the FNA specimens were examined with the Zeiss IBAS image analysis system to determine nuclear area, form (shape), diameter, density and integrated optical density (IOD). Nuclear area and IOD correlated most highly with the final diagnoses. Negative aspirates from benign cases and "false negatives" from malignant cases had similar morphometric values. Cells from adenocarcinoma had greater nuclear area and IOD values in cases cytologically labeled positive than in cytologically suspicious cases. Diagnoses based upon IOD values had a sensitivity and a specificity of 100% and 86%, respectively, while the use of nuclear area measurements produced values of 100% and 100%, respectively. These data indicate that nuclear area and IOD measurements can be valuable adjuncts to qualitative cytology for the diagnosis of pancreatic fine needle aspirates.     

Fine Needle Aspiration Cytology of Breast In Invasive Carcinoma of Tubular Type and In Radial Scar/Complex Sclerosing Lesions

Fine needle aspirates (FNA) from 31 invasive carcinomas of tubular type and 22 radial scar/complex sclerosing lesions (RS/CSL), diagnosed in Edinburgh between 1986 and 1991, were reviewed. the lesions in this study varied in size and palpability at presentation, but are of increasing interest in the differential diagnosis of non-palpable areas of increased mammographic density. In agreement with previously published information^1'5'8, it was found that the tubular cancers were usually selected for biopsy following aspiration, but less often definitively diagnosed as malignant. Nearly 50% of the RS/CSL group were correctly reported benign on cytology, but in 40%, biopsy was recommended to exclude malignancy. In addition, cytological features helpful in suggesting malignancy in aspirates from tubular cancers, also raised suspicion in aspirates from the RS/CSL group, with a risk of overdiagnosis of cancer.     

Histological examination of clots from cytological specimens: is this a worthwhile procedure?

A comparison of conventional cytology and clot histology was made on 174 serous fluids, fine needle aspirates (FNA) and other non‐gynaecological specimens. In eight cases (4.5%) this clot material contained malignant cells or cells suspicious of malignancy despite the absence of suspicious or malignant cells in conventionally prepared smears from the same specimen. In 11 cases (6.3%) the clot was negative, although conventional smears contained malignant or suspicious cells. A χ² test showed that there was no statistically significant difference between the number of positive diagnostic scores in each group with χ² of 0.223 (degrees of freedom=1), P=0.637. Examination of clot material from serous fluids and FNA aspirates is as effective as examination of conventional cytological preparations. Processing of clots from cytological aspirates for histological examination should be more widely adopted, and is applicable in all cytopathology laboratories.     

Interpretation of fine needle aspiration cytology of the breast: a comparison of cytological, frozen section, and final histological diagnoses

This study examines the performance of the preliminary, on-site interpretation by the pathologist of fine needle aspiration (FNA) cytology smears compared to the final cytology report, the frozen section diagnosis and the final histopathological report. We found that both the preliminary and the final cytology reports gave satisfactory results over the minimum standards for quality assurance required by both the Norwegian breast screening programme and the NHS BSP in the UK with the exception of the 'suspicious' rate. We noted that the preliminary report had fewer false negatives (2.1%) than the final report (4.3%). We show that an unequivocal cytological diagnosis of malignancy is a reliable diagnosis, and in cases where mammography/ultrasonography and clinical examination are in agreement with FNA, frozen section examination is unnecessary. However, cases with a suspicious or equivocal FNA should be considered for frozen section analysis.     

Value of fine needle aspiration cytology in the diagnosis of testicular neoplasms

In 403 patients with a clinical suspicion of a testicular neoplasm, fine needle aspiration (FNA) was performed on the scrotal mass in 380 cases and on an extrascrotal swelling in 23 cases. There were 109 unsatisfactory aspirates. Fluid was aspirated in 50 cases, and only normal testicular elements were obtained in 82 cases. The aspirate showed an inflammatory lesion in 104 cases. A diagnosis of malignancy or suspicious for malignancy was given in 52 and 6 cases, respectively. Histopathologic confirmation of malignancy was available for 30 cases, for which the aspirate had been reported as malignant in 23, suspicious for malignancy in 3, unsatisfactory in 2 and negative for malignancy in 2. There were no false-positive FNA cytodiagnoses. No local seeding of tumor by the FNA procedure was observed. Typing of the testicular tumors on the aspirates showed a problem in classifying teratocarcinomas.     

Ultrasound-guided fine needle aspiration cytology of impalpable breast lesions in a rural setting. Comparison of cytology with imaging and final outcome

OBJECTIVE: To analyze the effectiveness of fine needle aspiration (FNA) cytology in a multidisciplinary setting in rural Australia and to compare the imaging (mammographic and ultrasound) appearances and cytomorphologic findings with the final outcome. STUDY DESIGN: Prospective analysis of ultrasound-guided FNA cytology results from 426 women, aged 40-86 years, with screening-detected mammographic abnormalities. Cases of microcalcification, assessed mainly by stereotactatic core biopsy, were not included in the study. The FNAs were performed at a rural breast screening and assessment program in New South Wales, Australia, over a three-year period between May 1993 and May 1996. RESULTS: Imaging, FNA and combined imaging and FNA results from 426 women were as follows. The imaging diagnoses included 176 (41%) benign, 34 (8%) probably benign, 17 (4%) equivocal, 104 (24%) suspicious and 95 (23%) malignant cases. The FNA findings showed 59 (14%) no epithelial cells seen (nondiagnostic), 175 (41%) benign, 36 (8%) atypical, 41 (10%) suspicious and 115 (27%) malignant. Combined imaging and cytologic results comprised 224 (52.6%) benign, 10 (2.3%) atypical/equivocal, 59 (13.9%) suspicious and 133 (31.2%) malignant cases. All the malignant cases, by combined assessment, had malignant histology, and all the benign cases behaved in a benign fashion. In 80% of the suspicious lesions, the histologic diagnosis was malignant, but only 10% of the atypical/equivocal lesions had malignant histology. The positive predictive value of diagnosis of malignancy by combined imaging and FNA was 100%, and the false negative rate was 0%. CONCLUSION: Despite the recent surge in the popularity of core biopsy, FNA cytology of impalpable, mammographically detected lesions, when practiced in a multidisciplinary setting, is an extremely accurate test with high sensitivity, specificity, predictive values and efficacy. FNA cytology of the breast is a well-tolerated, relatively noninvasive test with a very low risk of complications. The sensitivity and positive predictive values for malignant and suspicious mammographic categories are also very high.     

Lymph node examination by fine needle aspiration in patients with known or suspected malignancy

In a series of more than 2,500 fine needle aspirates from multiple body sites, over 200 were clinically identified as lymph nodes from patients with known or suspected malignancy. The material was obtained using the easily manipulated Aspir-Gun with a 21-gauge or 22-gauge needle and syringe. Of the 200 lymph node specimens, 100 (50%) were cytologically reported as positive for malignancy. Ninety cases had surgical pathology specimens available for comparison with the fine needle aspiration (FNA) specimens. For the 88 of these cases with satisfactory FNA specimens, evaluation of the FNA results showed a predictive value of a positive result of 96.8%. These results compare favorably with those of surgical biopsy. The malignancies present in the lymph nodes included numerous adenocarcinomas from the breast, melanoma and pulmonary small-cell carcinoma. Six cases are briefly presented in which the FNA diagnosis was more problematic. While histologic examination of tissues or organs remains the desirable benchmark of comparison, the appropriate utilization of FNA cytology to guide therapy, particularly in a patient with previously diagnosed malignancy, may obviate the need for an open biopsy. The technique is convenient for patient and physician, useful for outpatients, relatively painless and provides good correlation between cytologic morphology and histopathology.     

5-year review and reappraisal of ultrasound-guided percutaneous transabdominal fine needle aspiration of pancreatic lesions

OBJECTIVE: To reevaluate the efficacy and safety offine needle aspiration cytology (FNAC) of pancreatic lesions performed by transabdominal approach. STUDY DESIGN: Retrospective 5-year (2001-2006) audit of all pancreatic FNA samples. RESULTS: This series includes 267 patients (88 men, 179 women). Seven cases (2.6%) yielded insufficient material for diagnosis; 260 cases were classified as benign (n=118) and malignant (n=142) lesions. Of the 118 benign aspirates, the cytodiagnosis was acute/chronic inflammation in 24, tuberculosis in 1, benign cyst in 10 and a benign aspirate, not otherwise specified, in the remaining 83 cases. Of the 142 malignant aspirates, the cytodiagnosis was adenocarcinoma in 126, neuroendocrine/carcinoid tumor in 7, papillary solid epithelial neoplasm in 2, mucinous cystadenocarcinoma in 2, acinar cell carcinoma in 1 and metastatic small cell carcinoma in lung in 4 cases. Cytohistologic correlation yielded a sensitivity of 81% and specificity of 100%. CONCLUSION: A spectrum of pancreatic lesions can be accurately diagnosed by the technique. The false negative rate can be minimized by proper positioning of the needle under guidance and adequate sampling. No postprocedural complications were encountered, proving that this procedure is safe if carried out by an experienced team in a hospital setting.     

Fine needle aspiration of pediatric abdominal masses. Cytologic and electron microscopic diagnosis.

Fine needle aspiration (FNA) was performed under ultrasound guidance on 17 abdominal masses in 16 pediatric patients at Baragwanath Hospital. The aspirated cellular material was assessed by conventional cytomorphology and by electron microscopy (EM). A diagnosis of malignancy was rendered for all 15 tumors that were adequately sampled (88.2%); the remaining 2 masses yielded insufficient material for either light microscopy or EM. Cytologic cell typing (including the use of EM) was successful in 12 of the 15 tumors (80%) as compared with the histologic diagnosis. EM was in agreement with the initial cytologic diagnosis in eight tumors, but corrected the initial impression in four tumors. The tumors with adequate aspirates included nine nephroblastomas and single examples of neuroblastoma, hepatoblastoma, non-Hodgkin's lymphoma, rhabdomyosarcoma, renal carcinoma and malignant rhabdoid tumor. The last three were not accurately typed by cytology plus EM. These preliminary results suggest that FNA cytology with adjunctive EM could become a useful technique in the preoperative assessment of pediatric abdominal tumors.     

A One Year Audit of Fine Needle Aspiration Cytology For the Pre-Operative Diagnosis of Breast Disease

In 1988, 985 patients presenting with breast disease, most with a palpable abnormality, were investigated by the triple approach (clinical examination, imaging and fine needle aspiration cytology [FNAC]). Using FNAC, 28% of patients were diagnosed as having carcinoma, 45% benign disease, 4% had suspicious cytology and 3% equivocal cytology. The remaining 20% had inadequate aspirates. Two false positive diagnoses of carcinoma were made (a false positive rate of 0.7%); one was a case of high grade non-Hodgkin's lymphoma and the other a papillary lesion with epithelial atypia. The false negative rate was 6.4%. Of these 49 patients, six had carcinoma-in-situ and 19 had low grade tumours. The absolute and complete sensitivities for the diagnosis of carcinoma in this series were 84.7% and 91.9% respectively and the absolute and complete specificities 99.7% and 98.3%, respectively. These figures compare favourably with those from other centres and confirm the efficacy of FNAC as part of the triple approach to the diagnosis of breast disease. The use of FNAC has resulted in a reduction in the number of Trucut and frozen section biopsies performed. Eighty three per cent of the patients with benign disease diagnosed by the triple approach have avoided excision biopsy, none of whom have subsequently been found to have carcinoma. Eighty patients with advanced breast carcinoma were spared operative intervention.     

Diagnostic utility of fine needle aspiration (FNA) cytology in HIV-infected patients with lymphadenopathy

reid a. j. c., miller r. f. and kocjan g. i. (1998) Cytopathology 9, 230–239
Diagnostic utility of fine needle aspiration (FNA) cytology in HIV-infected patients with lymphadenopathy
Sixty-five FNA cytology procedures were performed on lymph nodes in 52 HIV⁺ patients. Cervical lymph nodes were the commonest site of FNA cytology investigation (54%). The diagnoses were persistent generalized lymphadenopathy (38%), infection (17%), and malignancy (11%). Diagnosis could not be rendered in 25% of FNA cytology due to inadequate sampling. Of those with infection, mycobacterial disease was the commonest cause (91%), the diagnosis of which was enhanced by concurrent microbiological examination. Non-Hodgkin's lymphoma was the commonest malignancy. Sixteen lymph node FNA cytologies had subsequent tissue biopsy. There were two false-positive and four false-negative FNA cytologies. FNA cytology in HIV⁺ patients is most useful in the diagnosis of infection, obviating the need for tissue biopsy and allowing prompt initiation of treatment.     

Fine needle aspiration cytology of localized Leishmania lymphadenitis

Leishmania lymphadenitis, an uncommon cause of lymphadenopathy, is usually diagnosed by surgical biopsy performed because of suspicion of lymphoma. The cytopathologic features of this disease do not appear to have been previously described. This paper describes the findings in seven cases of Leishmania lymphadenitis diagnosed by fine needle aspiration (FNA) cytology. The identification of Leishman-Donovan bodies in epithelioid cells in the aspirates led to the cytologic diagnosis of Leishmania lymphadenitis, which was histologically confirmed in all cases. Since this disease is self-limiting and requires no treatment, FNA diagnosis is especially useful in that the patient can be spared more invasive diagnostic techniques.     

Fine needle aspiration cytology of granulomatous cryptococcosis of the lung

A cryptococcal infection was diagnosed in a patient with a history of immunoblastic non-Hodgkin's lymphoma by fine needle aspiration (FNA) cytology of a pulmonary nodule. This case illustrates that granulomatous inflammation can be appreciated by FNA cytology and, when seen, should result in a search for the specific organism. This case also reemphasizes the value of FNA cytology in the management and follow-up of patients with malignancy or those being treated with chemotherapy.     

Posters. P1 A 2‐year audit of thyroid fine needle aspiration cytology

Introduction Fine needle aspiration (FNA) cytology of the thyroid is a well‐established test in the clinical work‐up of patients with solitary nodules of the thyroid. Thyroid FNA does however have limitations and audit of diagnostic performance is important. Methods The histopathology archives of the Royal Victoria Hospital were searched for all thyroid resections and the histopathological diagnosis was correlated with the pre‐operative cytological diagnosis, where available. Special emphasis was placed on the accuracy of tumour diagnosis. Results A total of 173 cases were identified during the 2‐year period, of these 93 had available pre‐operative FNA. A total of 57 tumours were identified. A small number (six of 57) of significant discrepancies were identified. These included a malignant lymphoma diagnosed as Hashimoto's thyroiditis, a metastasis which the FNA had suggested was a medullary carcinoma and an insular carcinoma diagnosed as medullary carcinoma on FNA. False positives included a colloid cyst diagnosed as suspicious of malignancy and a cytological diagnosis of papillary carcinoma not confirmed on histology. Discussion At present, the majority of thyroid FNAs in our clinics are performed by surgeons and material is not routinely available for immunocytochemistry. In spite of these limitations, there were few major discrepancies. These might be reduced if pathologist aspirators were able to perform FNAs and collect material for further studies, where necessary. This would allow identification of medullary carcinomas and malignant lymphomas. Conclusion FNA of thyroid lesions is a useful investigation in our clinical setting, however, some areas of potential for improvement have been identified.