Evaluation of fine needle aspiration (FNA) cytology in the diagnosis of thyroid nodules

FNA cytology of 112 patients with thyroid nodules seen in a 5-year period in a general hospital setting, and the histology obtained from the 53 operated patients, were retrospectively analysed. the inadequacy rate of FNA cytology was 11%, sensitivity was 84% (16/19), specificity was 52% (15/29), positive predictive value was 53% (16/30) and negative predictive value was 83% (15/18). Extrapolating these figures to the whole study group a negative predictive value of 95% is put forward as a more realistic figure. the results and the clinical pitfalls of the use of FNA cytology in diagnosing thyroid nodules are discussed. the authors conclude that FNA cytology is a reliable first diagnostic step in the diagnosis of thyroid nodules, even in a general hospital setting.     

Fine needle aspiration cytology of "minimal" breast cancer

The value of fine needle aspiration (FNA) cytology in the diagnosis of "minimal" breast cancer was studied. Sixteen (76.2%) of 21 cases of invasive breast cancer less than 1.0 cm in diameter and 14 (73.3%) of 19 cases of noninvasive breast carcinoma were given a positive diagnosis by FNA cytology. One "suspicious" and the five false-negative diagnoses occurred in cases of invasive carcinoma; the reasons were considered to be either a faulty technique of needling the tumor or the presence of prominent fibrosis in the tumor. In noninvasive carcinoma, atypical cells were misdiagnosed in two of the five smears that had been originally reported as negative. The results of the retrospective analysis showed that FNA cytology had a higher accuracy in the diagnosis of small lesions than did radiologic and echographic criteria, and FNA cytology was thus used as the main criterion for deciding on the necessity for preoperative surgical biopsies.     

Analysis of fine needle aspiration cytology of the breast: a review of 1,297 cases and correlation with histologic diagnoses

OBJECTIVE: To evaluate the accuracy of fine needle aspiration (FNA) cytology of the breast and to ascertain its usefulness. STUDY DESIGN: The authors reviewed 1,297 cases of FNA cytology of the breast which were performed at Chonnam National University Hospital from 1999 to 2002. Cytologic diagnoses were compared with histologic diagnoses in 457 cases that underwent both cytologic and histologic examination. RESULTS: Of 1,297 cases, 1,201 (92.6%) were satisfactory and 96 (7.4%) unsatisfactory. Subsequent histologic examination was performed on 291 cases (29.7%) out of 981 "benign" lesions, 28 (73.7%) of 38 "suspicious," 124 (68.1%) of 182 "malignant" and 14 (14.6%) of 96 "unsatisfactory." FNA cytology revealed 77.7% sensitivity, 99.2% specificity, 98.4% positive predictive value and 88.0% negative predictive value. Diagnostic accuracy was 91.1%. Of the 291 benign cases on cytology, 35 cases were malignancy on histology. Of the 124 cases reported as malignant, 2 were benign. Interpretive error was the leading cause of false positive diagnoses. CONCLUSION: Although FNA cytology is a useful diagnostic procedure for the evaluation of breast lesions, it should be combined with other diagnostic modalities, such as physical examination, ultrasonography and mammography.     

Fine needle aspiration cytology of cystic parathyroid lesions. A cytomorphologic overlap with cystic lesions of the thyroid

Three cases of palpable cystic parathyroid nodules examined by fine needle aspiration (FNA) cytology are reported. Two of the three aspirates were incorrectly identified as thyroid neoplasms due to the presence of papillary clusters or microfollicles and grossly golden-brown cyst fluid. Histologic examination of these two nodules revealed partially cystic parathyroid adenomas. Aspirated material from the third patient yielded clear watery fluid, which was correctly identified as consistent with a parathyroid cyst. The diagnostic difficulties in the differentiation of parathyroid adenoma from thyroid carcinoma or adenoma are discussed, as is the utilization of assays for parathyroid hormone in making the FNA diagnosis of parathyroid lesions.     

Fine needle aspiration cytology of eyelid tumors

Fine needle aspiration (FNA) biopsy was performed on 19 patients with eyelid masses. Six of the patients also had preauricular/submandibular nodal enlargements aspirated. Histopathologic study was performed in ten of the cases. FNA cytology made the diagnosis of an epithelial malignancy in 17 cases (10 sebaceous carcinomas, 4 poorly differentiated carcinomas, 2 squamous cell carcinomas and 1 malignant melanoma). The diagnostic accuracy of FNA cytology in evaluating eyelid masses was thus 89.4%; there were two false-negative cases. All nodal FNA smears revealed metastases of the respective primary tumors. This study indicated that FNA cytology is a simple and efficient method for making the diagnosis of malignancy in eyelid masses, especially in those patients who are not suitable candidates for surgery. Subsequent nodal metastases and tumor recurrence were detected without difficulty using FNA smears.     

Fine needle aspiration cytology in the management of palpable benign and malignant breast disease. Correlation with clinical and mammographic findings

Two surgeons in a health maintenance organization group practice performed 280 fine needle aspirations (FNAs) on 257 palpable breast lesions in 200 patients. The cytology was interpreted by four pathologists at a community hospital. FNA cytology had a sensitivity of 96% and a specificity of 94% in these cases; there were no false-positive diagnoses of cancer. FNA cytology improved the identification of benign disease and decreased the risk of missing cancers. FNA cytology also improved the predictive value of mammographic information and was more helpful than mammography in demonstrating the need for biopsy of small palpable lesions that turned out to be "minimal" breast cancers.     

Role and accuracy of rapid on‐site evaluation of CT‐guided fine needle aspiration cytology of lung nodules

A. Fassina, M. Corradin, D. Zardo, R. Cappellesso, F. Corbetti and M. Fassan
Role and accuracy of rapid on‐site evaluation of CT‐guided fine needle aspiration cytology of lung nodules Objective: To prospectively investigate the role of trans‐thoracic fine needle aspiration cytology (FNA) and the value of rapid on‐site evaluation (ROSE) in the clinical management of patients with pulmonary nodules/masses. Computed tomography (CT)‐guided FNA is commonly employed for the diagnosis of lung lesions although its position in the diagnostic work‐up is still a matter of debate. Methods: We reviewed 311 patients (211 males and 100 females, mean age 69.5 years) admitted to the University of Padova from 2004 to 2008, correlating the results of cytology with the available histological findings obtained from biopsies, surgery or autopsy. Results: Smears were adequate in 305 cases (98%) and inadequate in six (2%); a diagnosis of malignancy was achieved in 263 cases (86.2%); 39 cases (12.8%) were classified as non‐malignant; and three cases (1%) were classified as suspect for malignancy. When correlated with histology, FNA with ROSE discriminated malignant versus non‐malignant lesions (Cohen’s kappa 0.78), with three false negatives (sensitivity 96.3%, specificity 100%). Moreover, a satisfactory overall agreement of 71.4% was achieved in differentiating the cancer histological types. Pneumothorax occurred in 13 cases, haemoptysis in four, and chest pain in three. A single aspiration was sufficient in 79.6% of patients; two aspirations were needed in 17.4% and three in 3%. The low complication rate was related to the limited number of aspirations needed due to ROSE. Conclusions: FNA with ROSE is a safe and useful tool in the diagnostic work‐up of lung cancer patients, with no contraindications to its use as the first diagnostic procedure for all patients with peripheral lung lesions. FNA with ROSE should be reconsidered in the guidelines for diagnosing and managing lung cancer.     

Utility of Ultrasound Versus Gene Expression Classifier in Thyroid Nodules with Atypia of Undetermined Significance

Objective: Thyroid nodules with fine-needle aspiration (FNA) cytology categorized as atypia of undetermined significance (AUS) often undergo additional diagnostic analysis with the Afirma Gene Expression Classifier (GEC), which classifies these as either high probability of being benign (GEC-B) or suspicious for malignancy (GEC-S). Our goal was to assess the clinical validity and utility of GEC in the evaluation of AUS cytology and evaluate the performance of ultrasonography (USG) for predicting malignancy in this subset.Methods: We conducted a study with a retrospective cohort of patients from January 2012 to January 2014 who had FNA of thyroid nodules >1 cm in size with AUS cytology.Results: Cleveland Clinic Florida has an overall prevalence of AUS of 5%. A total of 119 cases with nodules >1 cm in size were reported as AUS. Forty-eight (40.3%) had a GEC performed after the first FNA (AUS-1), and 27 of these were GEC-S. Of those 27, 21 went for surgery and 14 (66.6%) had thyroid cancer on histopathology. The remaining 71 with AUS-1 were sent for a second FNA: 19 nodules were benign and did not undergo further evaluation, while the remaining 52 were reported as AUS for the second consecutive time (AUS-2). AUS-2 samples were sent for GEC. Of these 52 AUS-2, 38 (73.1%) were reported as GEC-S. Thirty-five went for surgery and 32 (91.4%) had confirmed malignancy on histopathology. Positive predictive value (PPV) was 91.4% for AUS-2 and 66.6% for AUS-1. Moreover, AUS-2 nodules that were hypoechoic and solid on USG showed a PPV of 92% for malignancy.Conclusion: In our practice, the diagnostic accuracy to predict malignancy with GEC for AUS-1 nodules was poor (PPV, 66.6%). The PPV of GEC testing was markedly higher at 91.4% performed after two consecutive AUS cytologies. AUS-2 nodules that were solid and hypoechoic on USG also had a high probability to be malignant (PPV, 92%). We recommend repeat FNA on AUS-1 nodules rather than proceeding directly to GEC testing. Also, we suggest that among AUS-2 nodules, surgery can be recommended when USG shows solid and hypoechoic features with GEC testing reserved for the remainder.Abbreviations:AUS = atypia of undetermined significanceFNA = fine-needle aspirationGEC = gene expression classifierGEC-B = GEC-benignGEC-S = GEC-suspicious for malignancyNPV = negative predictive valuePPV = positive predictive valueUSG = ultrasonography     

Usefulness of core needle biopsy for the diagnosis of thyroid Burkitt’s lymphoma: a case report and review of the literature

Background

Thyroid lymphomas are an exceptional finding in patients with thyroid nodules. Burkitt’s lymphoma is one of the rarest and most aggressive forms of thyroid lymphomas, and its prognosis depends on the earliness of medical treatment. Given the rarity of this disease, making a prompt diagnosis can be challenging. For instance, fine-needle aspiration (FNA) cytology, which is the first-line diagnostic test that is performed in patients with thyroid nodules, is often not diagnostic in cases of thyroid lymphomas, with subsequent delay of the start of therapy.

Case presentation

Here we report the case of a 52-year-old woman presenting with a rapidly enlarging thyroid mass. Thyroid ultrasonography demonstrated a solid hypoechoic nodule. FNA cytology was only suggestive of a lymphoproliferative disorder and did not provide a definitive diagnosis. It is core needle biopsy (CNB) that helped us to overcome the limitations of routine FNA cytology, showing the presence of thyroid Burkitt’s lymphoma. Subsequent staging demonstrated bone marrow involvement. The early start of an intensive multi-agent chemotherapy resulted in complete disease remission. At 60 months after the diagnosis, the patient is alive and has not had any recurrence.

Conclusions

Clinicians should be aware that thyroid Burkitt’s lymphoma is an aggressive disease that needs to be treated with multi-agent chemotherapy as soon as possible. To diagnose it promptly, they should consider to order/perform a CNB in any patient with a rapidly enlarging thyroid mass that is suspicious for lymphoma.

     

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.     

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.     

The Value of Gross Visual Assessment of Specimen Adequacy for Liquid-Based Cytology During Ultrasound-Guided,Fine-Needle Aspiration of Thyroid Nodules

Objective: Major problems of fine-needle aspiration (FNA) of thyroid nodules arise due to nondiagnostic results caused by inadequately obtained FNA specimens. The purpose of this study was to evaluate the value of visual assessment of liquid-based cytology specimens during FNA of thyroid nodules for predicting sampling adequacy.Methods: For 3 months, visual assessment of FNA specimens was used for 534 consecutive nodules in 534 patients. The FNA specimens were visually graded immediately following aspiration for each nodule, and the visual grades were classified into 2 categories: inadequate (<6 cell groups) and adequate (>6 cell groups). The cytology results were classified as diagnostic or nondiagnostic based on the Bethesda system. We compared the ultrasound features and FNA characteristics between the diagnostic and nondiagnostic results. Multiple logistic regression analysis was used to determine factors independently predictive of nondiagnostic results. We also evaluated the interobserver agreement regarding the visual assessment.Results: Visual assessment was feasible in all patients, and the nondiagnostic rate was 11.6% (62 of 534). Nondiagnostic results were more frequent in the inadequate visual assessment group (38.1%) than in the adequate visual assessment group (10.5%) (P = .001). Independent predictive factors for nondiagnostic results were inadequate visual assessment (odds ratio, 5.18), >50% vascularity (odds ratio, 3.98), and macrocalcification (odds ratio, 3.60). Interobserver agreement for the prediction of visual assessment was good (κ value, 0.767; P<.001).Conclusion: Immediate visual assessment of a specimen during FNA of a thyroid nodule is a feasible method for predicting sampling adequacy.Abbreviations: FNA = fine-needle aspiration LBC = liquid-based cytology US = ultrasound     

Breast myeloma: a report of 3 cases with fine needle aspiration cytologic findings

BACKGROUND: Multiple myeloma of the breast is very rare, and the fine needle aspiration (FNA) findings have not been reported before. CASES: Two cases of multiple myeloma presented with bilateral breast nodules during treatment with chemotherapy. One case of multiple myeloma presented initially with a left breast mass. FNA smears of all 3 cases revealed numerous plasma cells, plasmablasts and multinucleated giant plasma cells. The smears were diagnosed as plasma cell tumors. Serum immunoelectrophoresis revealed IgG myeloma in 2 cases and IgA myeloma in 1. Marrow aspirates revealed > 30% plasma cells. Two patients died, and 1 was alive at this writing. CONCLUSION: The aspiration cytology findings of myeloma can be confuse, with primary and secondary tumors of the breast. The previous clinical history and ancillary studies, such as bone marrow study and serum immunoelectrophoresis, are essential to the correct diagnosis.     

Fine-needle aspiration of the thyroid: an overview

Thyroid nodules (TN) are a common clinical problem. Fine needle aspiration (FNA) of the thyroid now is practiced worldwide and proves to be the most economical and reliable diagnostic procedure to identify TNs that need surgical excision and TNs that can be managed conservatively. The key for the success of thyroid FNA consists of an adequate or representative cell sample and the expertise in thyroid cytology. The FNA cytologic manifestations of TNs may be classified into seven working cytodiagnostic groups consisting of a few heterogenous lesions each to facilitate the differential diagnosis. Recent application of diagnostic molecular techniques to aspirated thyroid cells proved to be useful in separating benign from malignant TNs in several cases of indeterminate lesions.     

Molecular characterization of small peripheral lung tumors based on the analysis of fine needle aspirates

The computed tomography (CT)-based early lung cancer diagnostic technologies allow the detection of very small stage I lung tumors. As part of these screening protocols any suspicious nodule has to be diagnosed morphologically, which requires CT-guided Fine Needle Aspiration, open biopsy or surgery. Fine Needle Aspiration (FNA) cytology is a well-recognised method for a rapid and accurate diagnosis of small lung tumors. Molecular analysis of the FNA specimens could complement cytology diagnosis by the characterization of the biological traits at the preoperative stage. In this study, we aimed to characterize the biological profile of 33 paraffin-embedded transthoracic FNA samples obtained from three groups of lung cancer patients: two groups of small early-detected lung adenocarcinomas (radiologically subsolid and solid nodules) and a third group of small metastatic adenocarcinomas. Genetic analysis was performed by fluorescence in situ hybridization using the four-color LAVysion probe. p53 and Ki-67 protein expression was also evaluated by immunocytochemistry. The samples showed gains for all targets analyzed; two cases had EGFR gene amplification and two cases had MYC amplification. There were no significant differences in the percentage of genetically malignant cells and the expression of Ki-67 among the three groups. However, p53 accumulation was significantly higher in the metastatic group compared to the subsolid early-detected group (P = 0.001). In conclusion, molecular analysis of FNA specimens may provide useful information at preoperative stages. In our series, a good prognostic profile in subsolid early detected adenocarcinomas is suggested.     

Repeat Diagnoses of Bethesda Category III Thyroid Nodules: What To Do Next?

Objectives

To assess the malignancy rates of thyroid nodules repeatedly classified as Bethesda category III on fine needle aspiration (FNA), and to suggest management guidelines for these lesions.

Methods

This is a retrospective study that included 395 thyroid nodules categorized as Bethesda III undergone either surgery or ultrasound (US) follow-up. There were 67 nodules classified a second time as Bethesda category III on repeat FNA. We compared malignancy rates, clinicopathologic and ultrasonographic characteristics between direct surgery and repeat FNA groups and between the initial and repeat Bethesda category III groups, each. And in the repeat Bethesda III group, clinicopathologic and US variables were compared between benign and malignant nodules.

Results

Incidence of concurrent cancer, underlying thyroiditis and positive BRAF mutation were significantly higher in 142 nodules with direct surgery than 243 nodules with repeat FNA (p < 0.05). Of the 395 nodules with Bethesda category III cytology on initial FNA, the malignancy rate was 59.5%. In 67 nodules with repeat Bethesda III classification, however, the malignancy rate was 73.1% (p < 0.05). However, none of the variables were significantly different between the initial Bethesda category III group and the repeat Bethesda category III group (p > 0.05). In the repeat Bethesda category III group, solid consistency, irregular/microlobulated margins, nonparallel shape, and number of suspicious findings or “suspicious malignant” US assessments were associated with a high malignancy rate (p < 0.05). On multivariate logistic regression analysis, the factor associated with malignancy in the repeat Bethesda category III group was irregular/microlobulated margin (odds ratio = 15.576; 95% CI, 2.097–115.6804, p = 0.007) with a sensitivity, specificity, positive and negative predictive values, and accuracy of 81.6%, 83.3%, 93.0%, 62.5% and 82.1%, respectively.

Conclusion

Thyroid nodules with repeated Bethesda category III classification and irregular/microlobulated margins on US are at increased risk of malignancy, and operative management should be considered as opposed to repeat FNA.     

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.     

Comparison of diagnostic results obtained by fine needle aspiration cytology and tru-cut or open biopsies

In seven cases fine needle aspiration (FNA) cytology provided a diagnosis of neoplasm when the Tru-Cut (TC) tissue biopsies (four cases) and open biopsies (three cases) were negative. The specimens consisted of two breast carcinomas, two metastatic neoplasms in the liver, one metastatic melanoma in inguinal lymph nodes, a retroperitoneal mass and a pelvic mass. In the two cases of mammary carcinoma, TC biopsies were negative and FNAs were diagnostic of carcinoma. TC biopsies in the two cases of questionable hepatic metastasis were negative, but FNAs demonstrated a malignant neoplasm. Open biopsy of a retroperitoneal mass failed to diagnose a neoplasm however, subsequent ultrasound-directed FNA demonstrated a neoplasm, possibly seminoma. FNA cytology of inguinal lymph nodes in one case was diagnostic of melanoma; open biopsy showed no neoplasm. Because of the FNA diagnosis, additional sections were made and the presence of melanoma was confirmed. This series demonstrates that FNA cytology should be considered the initial diagnostic procedure more often.     

Fine needle aspiration biopsy in the diagnosis of thyroid nodules

The fine needle aspiration (FNA) biopsies performed on thyroid nodules at Turku University Central Hospital from 1983 to 1988 were reviewed. Of the 1,054 total aspirated nodules, 194 were investigated histologically after thyroid surgery (191 cases) or at autopsy (3 cases). Two cases with an insufficient FNA sample, 4 with an incidental occult papillary carcinoma and 2 cases with carcinoma outside the nodule investigated by FNA biopsy were excluded from the series, leaving 186 histologically confirmed nodules in the final analysis. Three (3%) of the 107 cases with an FNA biopsy diagnosis of benign, 4 (8%) of the 52 with an FNA diagnosis of equivocal, 3 (20%) of the 15 with an FNA diagnosis of suspicious and all 12 (100%) with an FNA diagnosis of malignant were histologically malignant. If only an unequivocally malignant cytologic finding is considered positive, FNA biopsy had a diagnostic specificity of 100%, a sensitivity of 55% and an accuracy of 95% among the histologically confirmed cases. Follow-up revealed no cases of cancer among the 863 thyroids that were not explored surgically. It is concluded that FNA biopsy is a practical method with considerable diagnostic value in the evaluation of thyroid nodules.     

Cytology of melanotic schwannoma in a fine needle aspirate and pleural fluid. A case report

BACKGROUND: Melanotic schwannoma (MS) is a rare pigmented neural tumor most commonly occurring in the paraspinal region and involving spinal nerve roots and sympathetic ganglia. Few case reports describe the fine needle aspiration (FNA) cytology of MS. We report an additional case and for the first time describe the cytologic findings of MS in pleural fluid. CASE: A 44-year-old man presented with a 9.0-cm paraspinal mass associated with multiple lung nodules. FNA cytology of the paraspinal mass showed solitary and syncytially arranged spindled cells, with prominent nucleoli and variable amounts of cytoplasmic brown pigment. In pleural fluid, prominent isolated single cells were rounded and had a signet ring cell morphology. Tumor cells in both the aspirate and pleural fluid expressed S-100 protein and HMB-45. CONCLUSION: The FNA cytology findings of MS correlate well with the histologic findings. In pleural fluid, however, the cells are epithelioid, and some have a signet ring morphology, mimicking adenocarcinoma.