Primary pancreatic cystic neoplasms are being recognized with increasing frequency due to modern imaging techniques. In addition to the more common cystic neoplasms-serous cystadenoma, primary mucinous cystic neoplasm, and intraductal papillary mucinous neoplasm-there are many other less common neoplasms that appear as cystic lesions. These cystic neoplasms include solid pseudopapillary neoplasm of the pancreas (the most common rare cystic neoplasm), cystic neuroendocrine neoplasm, cystic degeneration of otherwise solid neoplasms, and then the exceedingly rare cystic acinar cell neoplasm, intraductal tubular neoplasm, angiomatous neoplasm, lymphoepithelial cysts (not true neoplasms), and few others of mesenchymal origin. While quite rare, the pancreatic surgeon should at the least consider these unusual neoplasms in the differential diagnosis of potentially benign or malignant cystic lesions of the pancreas. Moreover, each of these unusual neoplasms has their own natural history/tumor biology and may require a different level of operative aggressiveness to obtain the optimal outcome.

A 58-year-old woman was admitted to our hospital to optimize the management of her diabetes mellitus. A computed tomography (CT) scan showed a 30-mmdiameter, multilocular cyst in the head of the pancreas. The tumor markers, including DUPAN 2, SPAN-1, and carbohydrate antigen 19-9, were within the normal ranges. A contrast-enhanced CT scan showed a nonenhanced, multilocular cyst. Abdominal magnetic resonance imaging showed a multilocular cyst. Endoscopic retrograde cholangiopancreatography showed that the main pancreatic duct was normal. Based on these findings, we suspected a branch duct type intraductal papillary mucinous neoplasm. A distal pancreatectomy with a splenectomy was performed, since more of the mass was located on the dorsolateral side, inconsistent with the preoperative imaging results. On the resected specimen, a 4-cm-diameter, multilocular cyst containing serous fluid was found. Pathologically, the cyst wall was lined with squamous epithelium surrounded by abundant lymphoid tissue with follicles, consistent with a lymphoepithelial cyst of the pancreas, which is an unusual benign cyst.

CONTEXT Pancreatic cytopathology plays an important role in the diagnosis and management of patients with solid and cystic lesions of the pancreas. OBJECTIVE To serve as a practical guide to pancreatic cytopathology for the practicing pathologist. Data Sources.-A comprehensive assessment of the medical literature was performed. CONCLUSIONS We review pancreatic cytopathology, with specific discussions of its role in patient management, specimen types and specimen processing, specific diagnostic criteria, and the use of ancillary testing and advanced techniques.

OBJECTIVE To evaluate the diagnostic value of the gross appearance of aspirated material from endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) of pancreatic orperipancreatic cystic lesions. STUDY DESIGN This study focuses on nonneoplastic (peri)-pancreatic cystic lesions on EUS-FNA. Eight cases were identified with distinct gross appearances of aspirated material by the authors' experience and by computerized review. Gross observations are evaluated together with clinical data, radiologic findings, laboratory markers and cytologic and surgical microscopy findings. RESULTS Aspiration of cystic lesions often results in nonspecific cytologic findings. Gross and microscopic appearance of aspirated material can provide valuable information. We divide findings of 8 cystic lesions into 3 different patterns according to their gross appearance at on-site EUS-FNA: Pattern 1, 2 cases of biloma; Pattern 2, 1 case of lymphoepithelial cyst with sebaceous differentiation; Pattern 3, 3 cases of regular lymphoepithelial cysts and 2 cases ofpancreatic pseudocyst. CONCLUSION The full value of FNA is achieved only with the integrated approach, including the gross appearance of the cytology specimens. Certain unusual gross appearances of the aspirated material can add valuable information toward a pathologic diagnosis.

Lymphoepithelial cyst (LEC) of the pancreas is a rare lesion. Here, we report three cases that we encountered during 2007 in our institution, which were evaluated by endosonography (EUS) and fine needle aspiration (FNA). All three patients were male with ages ranging from 47 to 77 years. Each patient had a single, cystic mass of the body/tail of the pancreas that was found incidentally on CT scan. The size of the masses ranged from 3 to 6.5 cm radiologically. For each patient, EUS showed a well-circumscribed, lobulated mass with smooth contours; the remainder of the pancreas appeared normal without ductal dilation. FNA of all three masses demonstrated predominantly anucleated squamous cells, amorphous keratinous debris, and lymphocytes. Cholesterol crystals were present in one case. One patient underwent surgical resection and the diagnosis of LEC was confirmed histologically. In conclusion, pancreatic LECs are extremely rare, benign cystic lesions. FNA study may help to render a correct diagnosis and reduce unnecessary surgery.

BACKGROUND Lymphoepithelial cysts (LEC) of the pancreas are rare benign lesions that can be misdiagnosed as pancreatic masses or cystic neoplasms. With widespread use of abdominal cross-sectional imaging, more pancreatic lesions are being discovered, with EUS being used to further evaluate the abnormality. OBJECTIVE Our purpose was to describe EUS and cyst aspirate features of LEC of the pancreas. DESIGN Case series. SETTING Single tertiary referral center. PATIENTS Nine patients with lymphoepithelial cysts who underwent EUS-FNA. RESULTS Five male and 4 female patients were identified (mean age 51 years). All lesions were discovered by CT and described as "peripancreatic" in 67% of cases (6/9). EUS examination described a solid-appearing hypoechoic and heterogeneous mass with subtle postacoustic enhancement in 5 of 9 cases. Four lesions were described as purely cystic: 2 were septated, 1 was unilocular, and 1 had internal papillary fronds. Mean cyst size was 5.2 cm (range 1.7-12 cm). Cyst aspirates revealed a thick milky, creamy, or frothy aspirate in 56% of cases (5/9). Cyst cytologic examination revealed squamous material (nucleated/anucleated cells or keratin debris) in all cases. Lymphocytes were seen in 56% of aspirates (5/9). Carcinoembryonic antigen (CEA) levels were obtained in 5 cases (median 6.5 ng/mL [range 2.9-493.4 ng/mL]). Six patients have avoided surgery on the basis of EUS-FNA cytologic results confirming the diagnosis of LEC. Three patients underwent surgical resection: 2 for symptomatic lesions and 1 for concern for a mucinous cystic neoplasm given an elevated aspirate CEA level. Surgical pathologic examination confirmed LEC in each. LIMITATIONS Retrospective single-center study. CONCLUSIONS LEC should be considered whenever a large, well-defined solid or cystic peripheral pancreatic lesion is found. A thick milky, creamy, or frothy aspirate is common. The presence of squamous material and lymphocytes on cytologic examination is diagnostic of LEC. Aspirate CEA level may be elevated and should be considered in conjunction with cytologic results to avoid misdiagnosis as a mucinous cystic neoplasm. Asymptomatic LEC should be managed conservatively.

Lymphoepithelial cysts of the pancreas are extremely rare, benign, nonneoplastic cysts that may simulate pseudocysts or cystic neoplasm of the pancreas. Endosonographic and cytologic features of pancreatic lymphoepithelial cysts are poorly characterized because of their rarity. However, appropriate prospective diagnosis of pancreatic lymphoepithelial cysts using endoscopic ultrasound-guided fined needle aspiration (EUS-FNA) cytology may permit conservative management because of their benign nature. We conducted a MEDLINE search using the MeSH terms "pancreas","cyst" and identified 16 patients who were diagnosed with endosonography or computerized tomography (CT) guided fine needle aspiration. Usefulness and pitfalls of EUS- or CT-guided cyst fluid analysis in the pre-operative diagnosis of pancreatic lymphoepithelial cysts are discussed.

Cytology frequently has some role in preoperatively distinguishing pancreatic mucus-producing neoplasia (intraductal papillary mucinous neoplasms [IPMNs] and mucinous cystic neoplasms [MCNs]) from other pancreatic cysts. We evaluated all cytologic specimens at our institutions from resected pancreatic cystic lesions for lesional extracellular and cellular material. Lesional extracellular material was identified in 32 of 38 of the cytologic samples from cystic pancreatic mucus-producing neoplasms (28 of 31 IPMNs and 4 of 7 MCNs). Lesional cellular material was seen in 22 of 38 cases (17 of 31 IPMNs and 5 of 7 MCNs). Lesional material was more commonly identified in higher grade and invasive lesions. Lesional extracellular material was seen in 3 of 14 samples of other pancreatic cysts, and lesional cellular material was seen in 6 of 14 cases.

Acinar cell carcinoma (ACC) of the pancreas is extremely uncommon and its cytologic features have rarely been described. We describe the cytologic features of cases we have seen, review the literature regarding its cytologic features and discuss the pitfalls that may be encountered and the use of immunohistochemistry for its diagnosis. We searched our databases for all cases of histologically confirmed pancreatic ACC which had undergone prior fine needle aspiration (FNA) of the primary pancreatic lesion. The clinical histories, radiographic and sonographic findings, cytologic features, original cytologic diagnoses, and final histologic diagnoses were reviewed. Four cases of pancreatic ACC were found that had undergone FNA prior to histologic confirmation of the diagnoses. They were from 2 men and 2 women aged 50-75 yr. All masses were in the head of the pancreas, 2 had apparent peri-pancreatic adenopathy and 1 had an apparent liver metastasis. On review, all 4 had had diagnostic material on cytology samples. Original cytologic diagnoses included "acinar cell carcinoma,""pancreatic endocrine tumor,""favor neuroendocrine tumor, low-grade" and "non-diagnostic specimen." The cytologic features included small to moderate-sized loose groups with numerous single cells, prominent acinar formation, little anisonucleosis and prominent nucleoli. The cytologic features showed significant overlap with those of pancreatic endocrine tumors.

We studied the use of immunocytochemical analysis with material procured by endoscopic ultrasound-guided fine-needle aspiration (EUS-guided FNA) for the diagnosis of subepithelial intramural gastrointestinal (GI) mesenchymal neoplasms (SIGIMNs). We identified all EUS-guided FNA specimens of SIGIMNs that had undergone immunocytochemical analysis. Results were compared with follow-up histologic diagnoses. There were 95 aspirates that were diagnosed as GI mesenchymal tumors (GI stromal tumors [GISTs], n = 46), leiomyomas (n = 38), peripheral nerve sheath tumors (n = 5), and other neoplasms by cytologic examination. Immunoreactivity with antibodies to CD117 always predicted GIST at follow-up; 15 of 16 cases immunoreactive with antibodies to CD34 were found to be GISTs at follow-up. Strong immunoreactivity with antibodies to smooth muscle actin or desmin usually predicted a leiomyoma at follow-up aside from a single glomus tumor and a case with apparent nonneoplastic smooth muscle contaminant. When sufficient material is present, immunocytochemical analysis used with material obtained by EUS-guided FNA is highly predictive of final pathologic diagnosis.

OBJECTIVES Characterization of pancreatic cysts using endoscopic ultrasound-guided fine-needle aspiration includes cytological interpretation and chemical analysis. We prospectively analyzed the contribution of carcinoembryonic antigen (CEA) and cytological identification of extracellular mucin as predictors of mucinous neoplasia and malignancy. METHODS From January 2003 to October 2005, all patients referred to the University of Virginia with cystic lesions of the pancreas underwent endoscopic ultrasound-guided fine-needle aspiration with cytological evaluation and CEA level analysis. Data were collected prospectively and confirmed by resection or tissue biopsy. Univariate and multivariate analyses were performed on the following variables with regard to their ability to predict mucinous neoplasia: age (<55 or >55 years), sex, CEA level (<300 or >300 ng/mL), and cytological appreciation of extracellular mucin (positive or negative). P values less than 0.05 were considered significant. RESULTS A total of 43 patients were included in this study. There were 19 men and 24 women with a mean age of 63 +/- 14 years. The only complication was pancreatitis secondary to cyst leak in one patient. Multivariate analysis confirmed CEA level greater than 300 ng/mL (P= 0.007) and the identification of mucin (P < 0.001) as significant predictors. CONCLUSIONS With pancreatic cyst fluid analysis, the strongest predictor of mucinous neoplasia is the presence of identifiable mucin, followed by a CEA level greater than 300 ng/mL. The workup of cystic lesions of the pancreas should include chemical analysis for the CEA level and cytological examination with particular attention to extracellular mucin.

This review, based on the Hennepin County Medical Center experience and review of the literature, vastly covers the up-to-date role of endoscopic ultrasonography (EUS) and EUS-guided fine-needle aspiration (FNA) in evaluating tumorous lesions of the gastrointestinal tract and adjacent organs. Emphasis is given to the tumoral and nodal staging of esophageal, pulmonary, and pancreatic cancer. This review also discusses technical, pathological, and gastroenterologic aspects and the role of the pathologist and endosonographer in the evaluation of these lesions, as well as the corresponding FNA cytology and differential diagnosis.

Endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) has proven to be a valuable modality for the primary diagnosis and staging of gastrointestinal, and perigastrointestinal malignancy. Aside from assessing thoracic and abdominal lymph nodes and the liver for metastases, EUS can assess and sample the adrenal glands, which are frequently involved by metastatic disease, but can also harbor benign primary neoplasms. The cytology files at our institution were reviewed for all cases of EUS-guided FNA of the adrenal glands. Clinical histories, sonographic findings, and cytologic findings of all cases were reviewed. Results were compared with overall EUS-guided FNA performance and the performance of non-EUS-guided FNA of the adrenal. The utility of cell block immunohistochemistry (IHC) in these cases was reviewed. Between 1/1/00 and 5/15/04 there were 24 cases of EUS-guided FNA of the adrenal gland from 22 different patients (13 men; 9 women) at our institution. This represented 1.4% of overall EUS-guided FNA and 77% of adrenal gland FNA. Patient ages ranged from 37 to 86 yr (mean 69 +/- 11 yr). Most patients had other cancers or mass lesions and were being staged at the time of the procedure (19 of 22). Almost all FNAs were of the left adrenal gland (23 of 24). Lesion size ranged from 0.9 to 7.9 cm (mean 2.5 +/- 1.6 cm). Diagnostic material was present in all cases when compared with an overall EUS-guided FNA diagnostic rate of 88%. Material for cell block was present in 21 cases, and IHC was used in 3 cases. Final diagnoses were as follows: cortical tissue consistent with cortical adenoma (19), metastatic adenocarcinoma (3), pheochromocytoma (1), and adrenal cortical carcinoma (1). EUS-guided FNA of the adrenal gland is primarily used in the staging of other malignancies when lesions of the left adrenal are recognized sonographically. Diagnostic tissue is easily obtained, including material for cell block IHC, which allows definitive diagnosis in cases that present difficult differential diagnoses.

Chronic pancreatitis (CP) refers to a spectrum of changes generally seen after repeated injury that ranges histologically from mild fibrosis to extensive fibroinflammatory replacement of acinar tissue with accumulation of calcific debris. Because CP can share clinical and radiological features with malignancy, it often is sampled by fine-needle aspiration (FNA). The cytology files at Hennepin County Medical Center (HCMC) were searched for 20 consecutive cases of CP sampled by FNA. Clinical data and cytological findings were recorded. A spectrum of cytological findings typifies aspirates of CP. In most cases, mixed inflammation with debris and calcific material is present. Often, ductal cells are present and at most show mild atypia but generally appear organized. Often, fibrotic acinar tissue also is present while definitive islets are identified only rarely. Although these cytological findings were consistent with CP, 3 of 17 patients with follow-up were found to have pancreatic ductal adenocarcinoma.

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a proven modality for the diagnosis of primary pancreatic neoplasms. We describe our experience in diagnosing nonprimary pancreatic tumors by EUS-FNA. Cytology files were searched for all EUS-FNA of the pancreas for the period 2000-2002. All cases diagnosed as neoplasms were selected and those diagnosed as nonprimary pancreatic tumors were reviewed and analyzed. One hundred ninety-one of 468 cases were diagnosed as neoplasms. Eleven of these cases were diagnosed as nonprimary pancreatic tumors (2.4% of all diagnoses and 5.7% of all neoplasms). The diagnoses were supported by clinical history (n = 7), cytological findings (n = 11), cell block histology (n = 11), cell block immunohistochemistry (n = 6), and flow cytometry (n = 1). EUS-FNA is a safe and minimally invasive method for the diagnosis of nonprimary pancreatic neoplasms. Evaluation of clinical history, cytomorphology, and ancillary techniques, especially those applied to cell block material, are essential for accurate diagnoses.

All cell block specimens from pancreatic fine-needle aspirations (FNAs) obtained between January 1, 2002, and June 30, 2003, were reviewed for foamy gland adenocarcinoma (FGA). All smears from these cases were reviewed for cytologic features, including those previously noted in conventional pancreatic adenocarcinoma. Fifty-two cell block specimens showed adenocarcinoma. Of these, 12 (23%) showed histologic features of FGA. This pattern predominated in 6 cases and was present focally in 6 cases. Although there were relatively low nuclear/cytoplasmic (N/C) ratios, other features of adenocarcinoma were present universally, including loss of cohesiveness, nuclear overlap or loss of "honeycomb" architecture, anisonucleosis (> 4 to 1), irregular nuclear contours, prominent nucleoli, and atypical chromatin. Background necrosis was present in 8 cases. Distinct cell borders were present in 9 cases, and foamy cytoplasm was present in all cases. Pancreatic FGA is a recently described histologic pattern of pancreatic adenocarcinoma. It is not uncommon, and we identified the pattern, at least focally, in 23% of our FNA cell blocks. Although cytologic samples show low N/C ratios, most cytologic features of conventional pancreatic adenocarcinoma are present, and the diagnosis presents little additional difficulty.

Endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) allows for the sampling and diagnosis of lesions of the gastrointestinal system and adjacent tissues. It has also proved helpful with the sampling of lymphadenopathy both for the staging of malignancy and for the diagnosis of lymphadenopathy of other causes. We review our experience with EUS-guided FNA of lymph nodes. The cytology files were searched at Hennepin County Medical Center (HCMC) for all cases of lymph nodes sampled by EUS. Clinical history, biopsy site, diagnosis, and follow-up information (including ancillary testing) were reviewed. Between January 1, 2000 and December 5, 2002, 217 lymph nodes from 185 different patients were sampled by EUS at HCMC. Biopsy sites included 62 mediastinal, 9 paraesophageal, and 146 intra-abdominal lymph nodes. Diagnoses were as follows: metastatic non-small cell carcinoma (n = 69); benign, reactive lymph node (n = 76); granulomatous lymphadenopathy (n = 18); malignant lymphoma (n = 7); atypical-suspicious for malignancy (n = 5); metastatic small cell carcinoma (n = 2); necrotic debris (n = 4), and foreign material (n = 1); 35 cases were nondiagnostic (16.1%) in 22 of 185 patients (11.9%). Ancillary tests including flow cytometry, cytogenetics, and cultures were performed. EUS-guided FNA of mediastinal and intra-abdominal lymph nodes provides diagnostic material from which ancillary testing may be performed.

Lymphoepithelial cyst (LEC) of the pancreas is a rare benign lesion that may mimic cystic neoplasms. Diagnosis of pancreatic LEC has been depended on the elevation of serum carbohydrate antigen 19-9 (CA 19-9), biopsy of the cyst by endoscopic ultrasonography (EUS) and several abdominal imaging techniques including magnetic resonance imaging (MRI). However, it is very difficult to diagnose LEC of the pancreas preoperatively and excessive surgery has been done in spite of its benign nature. We herein report a case of pancreatic LEC which was preoperatively diagnosed by using in-phase and out-of-phase MRI and was successfully nucleated.

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BACKGROUND Yolk sac tumor (YST) of the ovary is a rare neoplasm typically affecting children and young women. We describe the cytomorphology of this tumor in ascitic fluid and discuss its differential diagnosis from other neoplasms. CASE Smear preparations of the ascitic fluid showed a predominance of clusters of malignant cells with vacuolated cytoplasm, mimicking a mucinous adenocarcinoma, and fewer syncytial-like and glandular structures. Hyaline globules were extremely rare. Immunocytochemistry was positive for alpha-fetoprotein. CONCLUSION The diagnosis of YST in ascitic fluid specimens may be challenging and requires the use of immunocytochemistry and the correlation of cytology with the remaining clinical and laboratory data.

BACKGROUND Preoperative diagnosis of pancreatic cystic neoplasms is problematic. We evaluated our experience with endoscopic ultrasound (EUS) to determine the utility of fine-needle aspiration cytology (FNAC) in surgical decision-making. METHODS Patients evaluated for pancreatic cysts with EUS fine-needle aspiration (FNA) from 3/1996-10/2003 were included. Patients undergoing both preoperative EUS-FNA and pancreatic resection were identified. FNAC read as a mucinous cystic neoplasm (MCN), suspicious for neoplasia, or mucinous epithelial/atypical cells were classified as "concerning." Cytology with no malignant cells was negative. FNAC read as indeterminate, atypical cells of undetermined significance, or possible contamination was nondiagnostic. RESULTS Of 95 patients evaluated with EUS FNAC, 29 underwent resection. On final pathology, 7/29 lesions (24%) were malignant [two neuroendocrine tumors, three adenocarcinomas, one invasive intraductal papillary mucinous neoplasm (IPMN), and one metastatic uterine tumor], 4/29 (14%) were benign (three serous cystadenomas and one chronic pancreatitis), and 18/29 (62%) were premalignant (ten MCNs and eight IPMNs). Seven patients had concerning FNAC. All seven harbored malignant or premalignant lesions. Nine patients had negative FNAC: three (33%) with benign lesions and six (67%) with premalignant lesions. Thirteen of the 29 patients (45%) had nondiagnostic FNAC with 12/13 (92%) harboring a malignant or premalignant lesion. Sensitivity, specificity, positive predictive value, and negative predictive value were 28%, 100%, 100%, and 18%, respectively. CONCLUSION The decision to proceed with nonoperative management should not be based on a negative or nondiagnostic FNAC alone, as 67% of negative and 92% of nondiagnostic specimens were associated with malignant or premalignant pathology.

Lymphoepithelial cyst (LEC) of the pancreas is a rare lesion. Here, we report three cases that we encountered during 2007 in our institution, which were evaluated by endosonography (EUS) and fine needle aspiration (FNA). All three patients were male with ages ranging from 47 to 77 years. Each patient had a single, cystic mass of the body/tail of the pancreas that was found incidentally on CT scan. The size of the masses ranged from 3 to 6.5 cm radiologically. For each patient, EUS showed a well-circumscribed, lobulated mass with smooth contours; the remainder of the pancreas appeared normal without ductal dilation. FNA of all three masses demonstrated predominantly anucleated squamous cells, amorphous keratinous debris, and lymphocytes. Cholesterol crystals were present in one case. One patient underwent surgical resection and the diagnosis of LEC was confirmed histologically. In conclusion, pancreatic LECs are extremely rare, benign cystic lesions. FNA study may help to render a correct diagnosis and reduce unnecessary surgery.

BACKGROUND Lymphoepithelial cysts (LEC) of the pancreas are rare benign lesions that can be misdiagnosed as pancreatic masses or cystic neoplasms. With widespread use of abdominal cross-sectional imaging, more pancreatic lesions are being discovered, with EUS being used to further evaluate the abnormality. OBJECTIVE Our purpose was to describe EUS and cyst aspirate features of LEC of the pancreas. DESIGN Case series. SETTING Single tertiary referral center. PATIENTS Nine patients with lymphoepithelial cysts who underwent EUS-FNA. RESULTS Five male and 4 female patients were identified (mean age 51 years). All lesions were discovered by CT and described as "peripancreatic" in 67% of cases (6/9). EUS examination described a solid-appearing hypoechoic and heterogeneous mass with subtle postacoustic enhancement in 5 of 9 cases. Four lesions were described as purely cystic: 2 were septated, 1 was unilocular, and 1 had internal papillary fronds. Mean cyst size was 5.2 cm (range 1.7-12 cm). Cyst aspirates revealed a thick milky, creamy, or frothy aspirate in 56% of cases (5/9). Cyst cytologic examination revealed squamous material (nucleated/anucleated cells or keratin debris) in all cases. Lymphocytes were seen in 56% of aspirates (5/9). Carcinoembryonic antigen (CEA) levels were obtained in 5 cases (median 6.5 ng/mL [range 2.9-493.4 ng/mL]). Six patients have avoided surgery on the basis of EUS-FNA cytologic results confirming the diagnosis of LEC. Three patients underwent surgical resection: 2 for symptomatic lesions and 1 for concern for a mucinous cystic neoplasm given an elevated aspirate CEA level. Surgical pathologic examination confirmed LEC in each. LIMITATIONS Retrospective single-center study. CONCLUSIONS LEC should be considered whenever a large, well-defined solid or cystic peripheral pancreatic lesion is found. A thick milky, creamy, or frothy aspirate is common. The presence of squamous material and lymphocytes on cytologic examination is diagnostic of LEC. Aspirate CEA level may be elevated and should be considered in conjunction with cytologic results to avoid misdiagnosis as a mucinous cystic neoplasm. Asymptomatic LEC should be managed conservatively.

Lymphoepithelial cysts of the pancreas are extremely rare, benign, nonneoplastic cysts that may simulate pseudocysts or cystic neoplasm of the pancreas. Endosonographic and cytologic features of pancreatic lymphoepithelial cysts are poorly characterized because of their rarity. However, appropriate prospective diagnosis of pancreatic lymphoepithelial cysts using endoscopic ultrasound-guided fined needle aspiration (EUS-FNA) cytology may permit conservative management because of their benign nature. We conducted a MEDLINE search using the MeSH terms "pancreas","cyst" and identified 16 patients who were diagnosed with endosonography or computerized tomography (CT) guided fine needle aspiration. Usefulness and pitfalls of EUS- or CT-guided cyst fluid analysis in the pre-operative diagnosis of pancreatic lymphoepithelial cysts are discussed.

Pure primary squamous cell carcinoma (SCC) is an extremely rare type of breast tumor. We report one of such cases in a 32-year-old woman, diagnosed by fine-needle aspiration cytology (FNAC). Aspiration smears were characterized by squamous cells, both isolated and in aggregates, at various stages of maturation. The tumor was excised, and the histologic sections confirmed the cytologic diagnosis. Pure primary SCC of the breast has a distinctive cytomorphologic appearance, and diagnosis of this tumor by FNAC is possible. For its diagnosis, the exclusion of SCC of local cutaneous structures and metastasis of distant squamous carcinoma are mandatory. Diagn. Cytopathol. 2007;35:429-432.(c) 2007 Wiley-Liss, Inc.

Three men and 2 women with ages ranging from 37 to 70 years, clinically and histologically confirmed solitary, palpable metastatic cancers to the thyroid (SMCT) and preoperative cytologic investigation of their thyroid lesions by fine-needle aspiration (FNA), were reviewed. Four patients were known to have a solid cancer treated by radical surgery 1 to 4 years prior [1 bronchogenic squamous cell carcinoma, 1 parotid adenoid cystic carcinoma, 1 renal cell carcinoma (RCC) and 1 cutaneous melanoma], and 1 patient had no past history of cancer. Direct smears prepared from the patients' thyroid FNAs were fixed in 95% ethanol and stained with the Papanicolaou method. In 3 cases, immunostaining of the aspirated tumor cells with thyroglobulin antibody was performed, and in 1 case an aspiration smear was stained with commercial HMB-45 antibody. A correct cytodiagnosis of metastatic cancer to the thyroid was made in all 5 cases. In 1 patient the thyroid FNA revealed a metastatic RCC that led to the discovery of a clinically occult RCC. All 5 patients died of metastatic disease 27 to 40 months after surgical resection of their SMCTs.

BACKGROUND The preoperative diagnosis of pancreatic serous cystadenoma (SCA) is important because as a typically benign tumor it can be treated expectantly, whereas many other cystic tumors require excision. This study examines the cytology, clinical and radiologic features, diagnostic accuracy of fine-needle aspiration (FNA), and potential pitfalls associated with this rare tumor. METHODS Cytomorphologic features were retrospectively reviewed from 28 FNAs of SCA from 21 patients. FNA biopsies were guided by percutaneous computed tomographic or ultrasonographic imaging in 10 cases and by endoscopic ultrasonographic imaging in 18 cases. Corresponding histology (14 tumors) and clinical/imaging findings were also evaluated. RESULTS Patients typically presented with upper abdominal discomfort or asymptomatically. Radiologically, a well-demarcated, multiloculated cystic mass involving the pancreatic head or uncinate process was common. Aspirates were sparsely cellular against a clean or granular, proteinaceous background. Tumor cells formed loose clusters or monolayered sheets composed of cuboidal cells with indistinct cell borders and granular or clear cytoplasm that was often stripped from the nucleus. Nuclei were small, round, with fine chromatin and indistinct nucleoli and devoid of mitotic activity. Seven (25%) of the aspirates were initially classified as "consistent with SCA," 6 (21%) as "no malignant cells," 3 (11%) as "nondiagnostic specimen," 3 (11%) as "suspicious for malignancy," 3 (11%) as "rare atypical cells," and 6 (21%) as "probably or consistent with mucinous cystic neoplasm." Features causing diagnostic difficulty were scant cellularity, papillary groups, nuclear atypia, and columnar cells mimicking those of mucinous neoplasms. Gastrointestinal (GI) epithelium and mucin also caused confusion. The detection of intracytoplasmic glycogen (3 of 6 cases) and cyst fluid analysis (2 of 2 cases) showing low viscosity and low or undetectable levels of carcinoembryonic antigen, CA 19.9, and amylase enhanced diagnostic confidence. CONCLUSIONS Diagnosing SCA by FNA is challenging. Familiarity with its morphologic spectrum, use of ancillary studies, and correlation with clinical/radiologic findings greatly improves diagnostic accuracy. Contaminating GI epithelium and mucin should be distinguished from components of a mucinous neoplasm.