Value of fine needle aspiration cytology in the initial diagnosis of Hodgkin's disease. Analysis of 188 cases with an emphasis on diagnostic pitfalls

OBJECTIVE: To evaluate the diagnostic accuracy and pitfalls of fine needle aspiration (FNA) cytology in the initial evaluation of Hodgkin's disease (HD) and to assess the influence of the pathologist's experience by comparing the results during two periods. STUDY DESIGN: A total of 170 cytodiagnoses of HD were reviewed and compared with those on the final histopathologic report. Thirty-three cases of HD with a previous, different cytologic diagnosis were also selected. In all the cases under study, FNA was performed as part of the initial diagnostic approach. From a practical perspective, diagnostic errors were divided into major or minor according to the consequences on patient management. RESULTS: Fifteen cytologic diagnoses of HD were followed by a different histologic diagnosis after lymph node biopsy. In 33 cases of HD an erroneous cytologic diagnosis was given prior to biopsy. The sensitivity of the series was 82.4% (86.1% excluding nonrepresentative cases). The positive predictive value reached 91.2%. Sensitivity varied from 79.3% in the first period (1982-1990) to 84.9% in the second (1991-1999) (83.3% and 88.2%, respectively, excluding nonrepresentative cases). Similarly, the positive predictive value increased from 89% to 92.8%. Diagnostic errors with important consequences for patient management diminished from 14 in the first period to 5 in the second. CONCLUSION: Cytology offers a rapid and accurate approach not only for the diagnosis of recurrent HD but also for its initial recognition. These results increase the capacity of FNA as a first-level diagnostic technique in the screening of lymphadenopathies.     

Fine needle aspiration cytology of parathyroid adenoma. A review of seven cases

The value of fine needle aspiration (FNA) cytology in the diagnosis of parathyroid adenomas was demonstrated by a cytohistologic review of seven cases. The cytologic patterns, which were characterized by numerous, mostly isolated epithelial cells and naked nuclei showing anisokaryosis and multiple nucleoli, were consistent with the histologic findings in this neoplasm, which should be considered in the differential (FNA) diagnosis of masses in the neck region. The only diagnostic problem is its differentiation from follicular thyroid neoplasms.     

Papillary breast lesions diagnosed on cytology. Profile of 65 cases

OBJECTIVE: To analyze the cytologic features of nipple discharge and fine needle aspiration (FNA) cytologic smears from breast lesions reported as showing papillary features and to correlate them with histopathologic features. STUDY DESIGN: The study group consisted of FNA smears and/or nipple discharge smears from 65 breast lesions diagnosed on cytology as duct papilloma, papillary lesion, fibrocystic condition, fibroadenoma, papillary neoplasm or papillary carcinoma. Cytomorphologic features assessed included cellularity, cell pattern (clusters, papillary, 3-dimensionality, etc.) and cell characteristics (monomorphism, pleomorphism, apocrine change, plasmacytoid features). Histological material was available for review and cytohistologic correlation in all cases. RESULTS: Forty-six specimens were FNA smears, and 16 were nipple discharge smears; in 3 cases FNA and nipple discharge cytologic smears were available for review. Cytologic study could predict the presence of a papillary pattern in all neoplasms with pure or focal papillary differentiation. There was an overlap in cytomorphologic features between papillary and nonpapillary benign lesions as well as between benign and malignant papillary neoplasms. Frank blood in the aspirate, cell dissociation and atypia, however, were more frequent in the last. CONCLUSION: Overlap of cytologic features in nonneoplastic and neoplastic benign papillary lesions and between benign and malignant papillary neoplasms necessitates histologic evaluation in all cases diagnosed as papillary on cytology. Since 49.2% of lesions showing papillary features on cytology prove to be malignant, all cases reported as papillary on cytology should be excised urgently for histologic assessment.     

Diagnostic use of mean nuclear area and nuclear DNA content in preoperative breast cancer cytology

OBJECTIVE: Fine needle aspiration (FNA) cytology of breast lumps is a routine procedure, and the diagnostic accuracy can be 95%. Occasional discrepancies arise, and it would be valuable to have additional parameters for accurate diagnosis. We evaluated nuclear DNA content and mean nuclear area (MNA) using image cytometry in the diagnosis of preoperative breast cancers by FNA in those with a discrepancy between clinical, radiologic and cytologic diagnoses. STUDY DESIGN: One hundred eighteen consecutive preoperative FNA samples were evaluated for nuclear DNA and MNA and were compared to cytologic and postoperative histologic diagnoses. RESULTS: Sensitivity, accuracy and positive predictive value of routine cytology were 95%, 90%, 95% as compared to nuclear DNA (66%, 66%, 96%) and MNA (61%, 61%, 97%). Combining these 3 parameters gave a sensitivity of 97%, accuracy of 94% and positive predictive value of 99%. CONCLUSION: These results demonstrate that nuclear DNA and MNA combined with routine cytology may be useful adjuncts in preoperative breast cancer cytologic diagnosis when discrepancies arise. This may lead to better and more accurate planning of treatment regimens in preoperative breast cancer patients.     

Cytomorphology of the variants of small-cell carcinoma of the lung

Cytologic classification of subtypes of small-cell carcinoma of the lung (SCCL) was retrospectively performed on respiratory material of 90 cases of lung carcinoma cytologically diagnosed as SCCL. Additionally, the cytologic material was reexamined for the presence of variants of SCCL in 68 cases of lung carcinoma whose types had not been conclusively defined by cytology. The type of lung cytology specimens reviewed were sputa, bronchial washings and brushings and fine needle aspirations. The study included review of pretreatment tumor histology, when present, and examination of the ultrastructure of the tumor in selected cases whose type had not been well defined by histology. Subtype recognition depended on the adequacy of the specimens rather than on the type of cytologic material examined. The cytologic subtyping was generally in agreement with the histologic subtyping of the tumor, except for cases in which SCCL was combined with other types of lung carcinoma, where certain discrepancies were noted.     

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.     

Fine needle aspiration biopsy versus sputum and bronchial material in the diagnosis of lung cancer. A comparative study of 168 patients

A group of 168 consecutive lung cancer patients in whom a definitive diagnosis of primary lung cancer was established either in a conventional cytologic specimen of sputum or bronchial material or in a specimen obtained by fine needle aspiration (FNA) biopsy was reviewed to compare the relative accuracies between the modalities of sputum and bronchial material on one hand versus FNA cytology on the other in the diagnosis of lung cancer. The patients included in the study were selected from a total of 1,093 patients who had been diagnosed and treated for lung cancer at Duke University Medical Center over the five-year period of January 1, 1980, through December 31, 1984. In 325 (29.8%) of the 1,093 patients, a definitive cancer diagnosis was established from histopathologic study alone, without any cytologic diagnoses. In 420 patients (38.4%), both histologic and cytologic material had been interpreted as being conclusively diagnostic for lung cancer. In 348 patients (31.8%), a cytologic diagnosis of lung cancer was made without a histologic confirmation. Thus, in a total of 768 (70.3%) of the 1,093 cases, a definitive cytologic diagnosis of cancer had been made. Of these 768 patients, 168 had been evaluated by both conventional respiratory cytologic methods (examination of sputum and bronchial material) and with FNA biopsy cytology. In 9 patients (5.4%), only conventional respiratory cytologic specimens were conclusively diagnostic for cancer. In 122 patients (72.6%), only the FNA biopsy specimen was diagnostic. In 37 patients (22.0%), both conventional respiratory specimens and FNA specimens yielded a definitive lung cancer diagnosis. The FNA specimen was the only positive cytologic specimen in 90.2% of large cell undifferentiated carcinomas, 79.5% of adenocarcinomas, 66.7% of small cell undifferentiated carcinomas and 58.2% of squamous cell carcinomas. In 26.5% of the patients, a diagnosis of cancer could have been established on conventional cytologic specimens, without the necessity of proceeding to percutaneous FNA biopsy. From this study, it is concluded that the techniques of conventional respiratory cytology and FNA biopsy cytology are complementary in the diagnosis of lung cancer. While the percentage of lung cancers diagnosed by FNA biopsy cytology alone is much greater than that obtained by conventional respiratory cytology alone, more than one-fourth of these cancers could be detected by the less invasive techniques of sputum collection and bronchoscopy.     

Role of fine needle aspiration cytology in nodular sclerosis variant of Hodgkin's lymphoma

OBJECTIVE: To assess the efficacy of fine needle aspiration cytology (FNAC) in the diagnosis of nodular sclerosis variant of Hodgkin's lymphoma (NSHL) and to analyze cytologic features that could help in subtyping a case of Hodgkin's lymphoma into this variant. STUDY DESIGN: FNAC smears of 18 histopathologically proven cases of NSHL were analyzed for a variety of features. RESULTS: On initial cytologic assessment, 14 of 18 cases were diagnosed as Hodgkin's lymphoma. No further subtyping was performed. In this retrospective analysis it was possible to revise the diagnosis in the remaining 4 cases. Of the various cytologic features analyzed, presence of numerous lacunar-type cells along with fibroblasts and collagenous material were useful pointers toward a diagnosis of nodular sclerosis variant. Fibroblasts were seen in 83.33%, collagenous material in 27.77% and numerous lacunar cells in 77.77%. CONCLUSION: Subtyping of NSHL based on cytologic features alone has been a matter of debate for a long time. Of the various subtypes, nodular sclerosis poses the greatest diagnostic difficulty. Though certain cytologic features may help in suggesting a diagnosis of nodular sclerosis variant, the primary role of fine needle aspiration is to diagnose a case of Hodgkin's lymphoma as such and advise histopathologic examination for further categorization.     

Fine needle aspiration cytodiagnosis of Hodgkin's disease and its subtypes. II. Subtyping by differential cell counts

Differential cell counts were performed on fine needle aspiration (FNA) smears from 96 cytologically diagnosed and subsequently biopsy-proven cases of Hodgkin's disease (HD). Reed-Sternberg cells and Hodgkin cells showed a definitely increasing trend in three major HD subtypes (as diagnosed on the smears): lymphocytic predominance (LP), mixed cellularity (MC) and lymphocytic depletion (LD). Lymphocytes, on the other hand, showed a decreasing trend between these subtypes. The differences in the percentages of Hodgkin cells, Reed-Sternberg cells and lymphocytes were highly significant (P less than .001). No trends (increasing or decreasing) were observed in the smear content of other reactive components (non-neoplastic histiocytes, eosinophils, plasma cells and neutrophils). In 88.0% to 95.0% of the cytologically diagnosed cases of LP, MC and LD subtypes, the percentages of Hodgkin cells plus Reed-Sternberg cells fell within a distinct range: less than 1.5% for LP, greater than or equal to 1.5% to less than 7.5% for MC and greater than or equal to 7.5% for LD. Analysis of the data based on histopathologic subtyping of the cases showed similar significant trends in the proportions of Hodgkin cells, Reed-Sternberg cells and lymphocytes, with 70.0% to 80.0% of the LP, MC and LD subtype cases within these ranges. These results demonstrate the validity of the subjective subtyping of HD on FNA smears in most cases.     

Fine needle aspiration cytology in the diagnosis of bone lesions

OBJECTIVE: Fine needle aspiration cytology (FNAC) in combination with radiological examination has recently gained clinical recognition for evaluating skeletal lesions. We evaluated our experience with the use of FNA in diagnosing bone lesions with emphasis on areas of difficulty and limitations. MATERIALS AND METHODS: Over a period of 5 years FNA was performed in 66 cases of bone lesions. Aspirations were done by cytopathologists using 22-gauge needle. Out of 66 cases unsatisfactory aspirate was obtained in 12 cases. Cytohistological correlation was available in 19 cases. RESULTS: Adequate aspirates were categorized into neoplastic (27 cases) and non-neoplastic (27 cases) lesions. Of the 27 neoplastic aspirates, 20 were malignant (12 primary, 8 metastatic deposits) and 7 were benign. In the malignant group osteosarcoma was correctly diagnosed in 3 cases while other 3 were labeled as sarcoma NOS because of lack of osteoid. Metastatic deposits were sub-typed in 6 cases; from renal cell carcinoma (3 cases), proststic adenocarcinoma, follicular carcinoma thyroid, and squamous cell carcinoma. Neoplastic group comprised of 6 cases of cysts and 21 cases of chronic osteomyelitis. Thirteen cases were diagnosed as tuberculous osteomyelitis. CONCLUSIONS: FNA is a frequent indication in metastases in the bone where distinct cytologic features can even identify an unknown primary. However, diagnosis of primary tumours of the bone is limited by precise subtyping of the tumours. FNA has emerged as a cost effective tool for initial diagnosis of both neoplastic and non-neoplastic lesions of the bone.     

Thyroid Cytology and Risk of Thyroid Cancer: Differences Among Indeterminate Specimens

ObjectiveTo assess the potential for stratification of indeterminate cytologic findings on fine-needle aspiration (FNA) of thyroid nodules in an effort to improve therapeutic strategies.MethodsWe attempted to determine the malignant risk associated with various indeterminate FNA cytologic patterns by correlation of specimens with the final histologic diagnosis. For this analysis, we identified 294 computerized medical records of surgically treated thyroid nodules during a 5-year period at our institution with the corresponding FNA cytology reports available.ResultsOf the 294 surgical cases, 162 with a positive or indeterminate cytologic report were selected, reviewed, and classified. Of 52 patients with positive cytologic findings on FNA, 51 (98%) had a final histologic report of a malignant thyroid nodule. Of 110 patients with indeterminate specimens, 30 (27%) had a final histologic diagnosis of thyroid carcinoma. The presence of nuclear atypia was predictive of thyroid carcinoma in 75% of patients, a Hürthle cell cytologic pattern was associated with a malignant thyroid nodule in 33%, and a hypercellular smear was suggestive of malignant involvement in 26% of cases. The lowest rate of malignant potential was associated with cytologic microfollicular and scant colloid alone subtype (6%).ConclusionThe results of this study show that indeterminate thyroid cytologic specimens can be subdivided into groups with different malignant risks. A microfollicular cytologic pattern in the absence of a hypercellular smear or nuclear atypia does not support a recommendation of surgical treatment. A malignant cytologic diagnosis has a high positive predictive value for detection of thyroid cancer. (Endocr Pract. 2004;10:330-334)     

Ki-1-positive anaplastic large cell lymphoma initially diagnosed as Hodgkin's disease by fine needle aspiration (FNA) cytology

A 45-year-old male presented with a large mass in the left axilla. FNA cytology was interpreted as Hodgkin's disease (HD), lymphocyte depletion (LD) type, but histopathologic and immunohistochemical examination showed features of Ki-1-positive anaplastic large cell lymphoma. Unrepresentative sampling by the FNA from the tumour periphery resulted in a false impression of dual reactive and neoplastic cell populations. which together with the frequent Reed-Sternberg-like cells led to the initial erroneous impression of HD. Therefore, the cytologic diagnosis of HD, LD should be approached with caution.     

Computed tomography-guided fine needle aspiration of peripheral lung opacities. An initial diagnostic procedure?

OBJECTIVE: To evaluate the results of computed tomography (CT)-guided fine needle aspiration (FNA) cytology following negative fiberoptic bronchoscopy and sputum cytology. STUDY DESIGN: Retrospective study of 64 patients who underwent CT-guided needle aspiration of lung opacities over one year. Following a review of the CT studies, patients were selected according to image characteristics of a primary neoplasm and pleural effusion in cases with pleural lesions. The lesions were classified into three categories--intrapulmonary and peripheral pulmonary, pleuropulmonary and pleural--and were localized and aspirated under CT using a fine needle (22-23 gauge) for obtaining cellular material. Lesions diagnosed as benign on FNA cytology were followed by serial CT scans for a period of two years at six-month intervals. RESULTS: Thirty-nine of 64 (61%) lesions were diagnosed as malignant on FNA cytology and 25 of 64 (39%) as benign. There was one false negative case. There were no serious complications from the procedure. CONCLUSION: FNA under CT guidance may be applied as the initial procedure in the diagnosis of peripheral malignant pulmonary lesions, rendering a high diagnostic yield.     

Clinicopathologic analysis of fine needle aspiration cytology of the thyroid. A review of 1,613 cases and correlation with histopathologic diagnoses

OBJECTIVE: To evaluate the accuracy of fine needle aspiration (FNA) of thyroid lesions at our institution and to ascertain its usefulness in determining the therapeutic approach. STUDY DESIGN: The authors reviewed the results of 1,613 cases of FNA cytology of thyroid nodules performed from 1999 to 2001 at the Department of Pathology, Chonnam National University Hospital. Cytologic diagnoses were compared with histologic diagnoses in 207 cases that included both FNA and thyroid surgery. RESULTS: The sensitivity for the detection of neoplasms (carcinoma and follicular adenoma) was 78.4% and the specificity 98.2%. A false positive diagnosis was made in 1 case (1.8%) and false negative ones in 28 cases (21.5%). The diagnostic accuracy was 84.4%, with a positive predictive value of 99.0% and negative predictive value of 66.3%. The predictive value of a cytologic diagnosis was 100% in papillary carcinoma. CONCLUSION: FNA is a useful test in determining the therapeutic approach of thyroid lesions.     

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.     

Fine needle aspiration cytology of the pancreas. A retrospective study of 73 cases

Retrospective review of pancreatic fine needle aspiration (FNA) biopsy specimens collected with computed tomographic guidance from 73 patients between 1980 and 1985 at the Medical Center of Delaware was performed to determine the accuracy of the procedure in our hands and to identify possible problem areas for cytologic diagnosis. When compared with clinical data or tissue diagnosis, FNA had a sensitivity for the detection of pancreatic carcinoma of 67.7%. The predictive value of a negative result was only 23.1%. When compared to the cytologic diagnosis made at the time of review, FNA had a sensitivity of 100%, but a single false-positive case was identified. In addition to the majority of probable pancreatic ductal carcinomas, a hepatoma and a lymphoma were detected. Cases of primary pancreatic carcinoma were classified by cytologic features, but all groups had dismal three-to-six-month median survivals, regardless of the degree of tumor differentiation. Survival times were similarly low for patients with negative pancreatic FNAs. The low patient survival times, regardless of FNA diagnosis, support the value of avoiding laparotomy in these patients and confirm the high false-negative rate of the procedure.     

The role of fine needle aspiration cytology in the diagnosis of lymphoma

The accuracy of fine needle aspiration (FNA) cytology for the diagnosis of lymphoma and other hematolymphoid malignancies was investigated by a review of 158 FNA specimens from 143 patients. Patients included in the study had either a diagnosis of a hematolymphoid malignancy by FNA cytology or a biopsy diagnosis of lymphoma that was preceded by FNA cytology. Biopsy specimens were obtained from 85% of the patients. Of the 158 needle aspirates, 118 (75%) were diagnosed as lymphoma, 13 (8%) as suspicious of lymphoma, 8 (5%) as myelomas, 3 (2%) as leukemias, 12 (8%) as positive for malignancy and 4 (2%) as negative for malignancy. Two of the 118 needle aspirates diagnosed as lymphoma were false positives while 3 of 13 diagnosed as suspicious for lymphoma were found to be benign. Overall, there were four false negatives. Morphologic subclassification of the lymphomas, originally attempted for 60 needle aspirates, was identical to the histologic subclassification in 51 cases (85%). FNA cytology provided the initial diagnosis of a hematolymphoid malignancy in 51% of the cases and allowed the documentation of recurrent disease in 49%. The results demonstrate the usefulness of FNA cytology for the diagnosis and management of patients with lymphoma.     

Cytohistologic correlation of cirrhosis and hepatocellular carcinoma. Pitfall in diagnosis?

OBJECTIVE: To compare the diagnostic criteria for cirrhosis and hepatocellular carcinoma (HCC) noted on liver fine needle aspirates (FNAs) and their corresponding liver needle core biopsies (NCBs). STUDY DESIGN: We reviewed FNA slides from 15 cases of cirrhosis and 6 cases of HCC and their corresponding NCBs. We compared a variety of specific nonarchitectural criteria, including small cell dysplasia (SCD) and large cell dysplasia (LCD), for distinguishing cirrhosis from HCC. RESULTS: FNA smears diagnostically correlated with NCBs. The cytologic criterion with the greatest correlation in predicting HCC on FNA was SCD. This was not noted in all the core biopsies, probably due to sampling error. LCD was seen more frequently in cirrhosis than HCC on both cytology and histology and therefore was not a criterion useful in establishing a diagnosis of malignancy. The remaining cytologic criteria had good correlations but did not aid in diagnosing HCC. CONCLUSION: FNA has good cytohistologic correlation with NCB for both cirrhosis and HCC. There is an association of SCD with HCC; however, LCD is not a reliable "precancerous" change as it is commonly seen in cirrhosis and HCC. Therefore, the presence of SCD on FNA should be reported and is an indication for close clinical follow-up to exclude HCC.     

Fine needle aspiration cytology of primary bone lesions

Fine needle aspiration (FNA) cytologic findings were compared with the results of conventional histology in a series of primary bone lesions to determine the diagnostic accuracy of FNA cytology. The series included 12 osteogenic sarcomas, 4 Ewing's sarcomas, 3 chordomas, 3 myelomas, 2 chondrosarcomas, 2 undifferentiated sarcomas and 1 case each of normal bone and marrow elements, lymphoma and giant-cell tumor. All aspirates yielded adequate material for smear diagnosis, and all 29 cases were correctly identified as benign or malignant by cytology. In 19 cases (66%), specific cytologic diagnoses were rendered and histologically confirmed. This series is compared with other published series of bone aspirations in terms of technique, accuracy and ability to obtain diagnostic material. The importance of technique, radiographic investigations and experience in performing the aspirations in achieving a high diagnostic yield is emphasized.     

Fine needle aspiration cytology of soft tissue tumors

OBJECTIVE: To review of the value of fine needle aspiration (FNA) cytology in the diagnosis of soft tissue tumors (STT). STUDY DESIGN: A review of the literature was coupled with the authors' experience with indications, diagnostic specificity and pitfalls; clinical information; and the final cytology report. RESULTS: Over the last few years, FNA has come to be considered a valuable tool in the management of STT in that it affords a specificity of > 90%. FNA is of particular value in any subcutaneous lesion > 5 cm, in all pediatric tumors and whenever direct incision biopsy is particularly contraindicated. Material from aspirates can be used to obtain cytologic smears for conventional staining, special pigment identification, histochemical techniques, cell blocks for paraffin embedding and ancillary techniques (immunocytochemistry, electron microscopy, and densitometric and cytogenetic analyses). The cytologic diagnosis, like its histologic counterpart, should be based on a correct evaluation of clinical data (age, localization, size, effect on bone, nerve and vessel involvement), radiologic information, cytologic findings (architectural pattern, cell and stroma characteristics) and results of special staining techniques. The final cytology report should place the tumor in one of three basic categories: benign, malignant, and inconclusive or undetermined. Wherever possible, a histopathologic diagnosis should also be provided, either based on purely cytologic criteria or aided by ancillary techniques. CONCLUSION: FNA does not present major complications and permits a swift, preliminary diagnosis in a large number of cases. The method is most effective when the aspiration is performed by an experienced pathologist.