Cyst fluid cytology and chemical features in a case of lymphoepithelial cyst of the pancreas: A rare and difficult preoperative diagnosis

Pancreatic Cystic Lesions: A Focused Review on Cyst Clinicopathological Features and Advanced Diagnostics

Macroscopic, endomicroscopic, and histologic findings and correlation are an integral part of the diagnostic evaluation of pancreatic cystic lesions (PCLs), as complementing morphologic features seen by different specialties are combined to contribute to a final diagnosis. However, malignancy risk stratification of PCLs with worrisome features can still be challenging even after endoscopic ultrasound guided-fine needle aspiration (EUS-FNA) with cytological evaluation. This review aims to summarize cyst clinicopathological features from the pathologists' perspective, coupled with knowledge from advanced diagnostics-confocal laser endomicroscopy and cyst fluid molecular analysis, to demonstrate the state-of-art risk stratification of PCLs. This review includes illustrative photos of surgical specimens, endomicroscopic and histologic images, and a summary of cyst fluid molecular markers.

Cytologic Assessment of Cystic/Intraductal Lesions of the Pancreatobiliary Tract

CONTEXT.—

Because of new and improved imaging techniques, cystic/intraductal pancreatobiliary tract lesions are increasingly being discovered, and brushings or endoscopic ultrasound/computed tomography/magnetic resonance imaging-guided fine-needle aspiration biopsies from these lesions have become an integral part of pathologists' daily practice. Because patient management has become increasingly conservative, accurate preoperative diagnosis is critical. Cytologic distinction of low-risk (pseudocysts, serous cystadenoma, lymphoepithelial cysts, and squamoid cysts of the pancreatic duct) from high-risk pancreatic cysts (intraductal papillary mucinous neoplasm and mucinous cystic neoplasm) requires incorporation of clinical, radiologic, and cytologic findings, in conjunction with chemical and molecular analysis of cyst fluid. Cytopathologists must ensure appropriate specimen triage, along with cytologic interpretation, cyst classification, and even grading of some (mucinous) cysts. Epithelial atypia in mucinous cysts (intraductal papillary mucinous neoplasm and mucinous cystic neoplasm) has transitioned from a 3-tiered to a 2-tiered classification system, and intraductal oncocytic papillary neoplasms and intraductal tubulopapillary neoplasms have been separately reclassified because of their distinctive clinicopathologic characteristics. Because these lesions may be sampled on brushing or fine-needle aspiration biopsy, knowledge of their cytomorphology is critical.

OBJECTIVE.—

To use an integrated, multidisciplinary approach for the evaluation of cystic/intraductal pancreatobiliary tract lesions (incorporating clinical, radiologic, and cytologic findings with [chemical/molecular] cyst fluid analysis and ancillary stains) for definitive diagnosis and classification.

DATA SOURCES.—

Review of current literature on the cytopathology of cystic/intraductal pancreatobiliary tract lesions.

CONCLUSIONS.—

Our knowledge/understanding of recent updates in cystic/intraductal pancreatobiliary lesions can ensure that cytopathologists appropriately triage specimens, judiciously use and interpret ancillary studies, and incorporate the studies into reporting.

Intraductal papillary mucinous neoplasm of the pancreas: Cytomorphology, imaging, molecular profile, and prognosis

BACKGROUND

Intraductal papillary mucinous neoplasm (IPMN) constitutes up to 20% of all pancreatic resections, and has been increasing in recent years. Histomorphological findings of IPMN are well established; however, there are not many published papers regarding the cytological findings of IPMN on fine needle aspiration (FNA) specimens. We review the cytomorphological features, molecular profile, imaging findings, and prognosis of IPMN.

METHODS

The English literature was thoroughly searched with key phrases containing IPMN.

OBSERVATIONS

IPMN is a rare entity, affecting men and women equally and is usually diagnosed at the age of 60-70 years. The characteristic imaging features include a cystic lesion with associated dilatation of the main or branch pancreatic duct, and atrophy of surrounding pancreatic parenchyma. Cytomorphological features of IPMN include papillary fragments of mucinous epithelium in a background of abundant thick extracellular mucin, a hallmark feature. IPMNs should be evaluated for high-grade dysplasia, which manifests with nuclear atypia, nuclear moulding, prominent nucleoli, nuclear irregularity, and cellular crowding. Molecular profiling of IPMN along with carcinoembryonic antigen and amylase levels is useful in predicting malignancy or high-grade dysplasia arising in IPMN. Overall, the prognosis of IPMN is excellent except in those cases with high-grade dysplasia and malignant transformation. Postoperative surveillance is required for resected IPMNs.

CONCLUSION

IPMN requires a multidisciplinary approach for management. Cytomorphological findings of IPMN on FNA, in conjunction with tumour markers in pancreatic fluid cytology and imaging findings, are of paramount importance in clinical decision-making for IPMN.

Endoscopic Ultrasound-Guided Fine Needle Aspiration Cytologic Evaluation of Intraductal Papillary Mucinous Neoplasm and Mucinous Cystic Neoplasms of Pancreas

OBJECTIVES

To evaluate the role of endoscopic ultrasound-guided fine needle aspiration cytology in identifying mucinous cystic lesions (MCLs) in histologically proven cases of intraductal papillary mucinous neoplasm (IPMN) or mucinous cystic neoplasm (MCN) and risk of malignancy associated with each cytologic category based on the Papanicolaou Society of Cytopathology (PSC) guidelines.

METHODS

All resected cases with histologic diagnosis of IPMN or MCN at our institution from January 1, 2004, to August 31, 2019, with associated cytology were included. Available cytology slides of nondiagnostic (ND), negative/benign (BN), and atypical cytology (AC) cases were reviewed and reclassified based on the PSC guidelines.

RESULTS

A total of 120 cases were identified, including 57 IPMNs with low-grade or moderate dysplasia (LGD/MD) and high-grade dysplasia (HGD), 34 MCNs with LGD/MD or HGD, and 29 IPMNs with invasive malignancy. After cytology slide review and reclassification, we observed that ND and BN cases were paucicellular and lacked ancillary testing (carcinoembryonic antigen levels or KRAS mutation analysis). The risk-of-malignancy rates were 33% for ND, 11% for BN, 28.5% for AC, 17% for MCL, and 100% for suspicious/positive cytologic diagnosis.

CONCLUSIONS

A multidisciplinary approach including combined use of cytology and ancillary testing is helpful in establishing a diagnosis of MCL and identifying associated malignancy.

Endoscopic Ultrasound Imaging for Diagnosing and Treating Pancreatic Cysts

Cystic pancreatic lesions are increasingly diagnosed owing to the abundant use of cross-sectional imaging. Given their malignant potential, true pancreatic cysts should be considered for resection or periodic follow-up. Cystic lesions of the pancreas (CLPs) require further evaluation and management. Therefore, it is important to establish a solid diagnosis at the time of detection. Endoscopic ultrasound examination is the imaging modality of choice. Fine needle aspiration provides fluid for cytologic, biochemical, and molecular assays to classify lesions and predict biological behavior. This review provides an overview of the diagnosis and management of various types of commonly encountered true CLPs.

Endoscopic ultrasound characteristics of pancreatic lymphoepithelial cysts: A case series from a large referral center

BACKGROUND AND OBJECTIVES

Lymphoepithelial cysts (LECs) of the pancreas are benign lesions that can mimic cystic neoplasms on imaging. Endoscopic ultrasound (EUS) features have not been well described. We aimed to describe the clinical and EUS characteristics of LECs and the present outcomes of management at a high-volume referral center.

MATERIALS AND METHODS

We identified patients who underwent EUS and were found to have LECs based on fine-needle aspiration (FNA) cytology or surgical pathology from existing databases. EUS features, imaging characteristics, and pathology results were described.

RESULTS

Sixteen patients were found to have 17 LECs. The mean size was 33 mm ± 15 mm. Locations within the pancreas included 10 lesions in the tail, 3 in the body, 1 in the uncinate process; the remaining 3 were exophytic. Six lesions were anechoic, 6 were hypoechoic, and 5 had mixed echogenicity. Nine lesions had mixed solid/cystic components, 7 were purely cystic, and 1 was solid. Cyst fluid was thick or viscous in six cases and thin in three. Eleven patients had diagnostic cytopathology. Six patients ultimately underwent surgery due to symptoms, nondiagnostic FNA, or other clinical concerns for malignancy.

CONCLUSIONS

Pancreatic LECs have variable morphology and echogenicity on EUS, but the appearance of a cyst with variable solid and cystic components combined with the appearance of thick, turbid, and viscous aspirate should raise suspicion for an LEC. The majority of patients with LECs at our center avoided surgery for LECs on the basis of diagnostic EUS-FNA.

Lymphoepithelial Cysts of the Pancreas: CT and MRI Features

Objective: Describe CT and MRI features of the lymphoepithelial cyst (LEC) of the pancreas. Methods: The authors identified 13 cases of LEC by searching their institutional electronic medical archives from 2004 to 2020. All of the patients had CT scans and six patients had both a CT and MRI. The final diagnosis was established either by fine-needle aspiration with cytopathology (n=6) or surgical resection (n=7). Results: The mean diameter of the cysts was 36 mm (range: 6–93 mm). Almost all of the cysts were exophytic (92%) and solitary (85%), favouring the tail (54%) or body (38%) of the pancreas. LECs were either oval (62%) or round (39%) and had well-defined contours. All LECs showed T2 hyperintensity and T1 hypointensity; however, the signal was heterogeneous. Diffusion-weighted imaging showed restricted diffusion in all cases. On CT, LECs commonly showed complex fluid density (>15 HU) with no visible septation, enhancement or calcification. Conclusion: LECs have a distinguishing feature on MRI, which is restricted diffusion on diffusion-weighted imaging. This is presumably secondary to the presence of keratin, which can be a helpful feature differentiating LECs from other pancreatic cystic neoplasms. Besides this, LECs predominantly appear as solitary and exophytic lesions, with complex fluid density on CT and heterogeneous hypointense T1 and heterogenous hyperintense T2 signal on MRI.

Lymphoepithelial cyst of the pancreas: an analysis of 117 patients

OBJECTIVES

Lymphoepithelial cyst (LEC) of the pancreas is an unusual and benign cystic tumor. Accurate preoperative diagnosis is difficult; hence, most of pancreatic LECs are resected. The aim was to describe clinicopathological features of pancreatic LEC to guide appropriate management.

METHODS

We retrospectively collected data about LEC patients treated in our department between 1987 and 2012 and added cases from review of the literature during the same period.

RESULTS

One hundred seventeen cases (3 from our institution and 114 from literature review) were identified. Most patients were men (78%). The discovery was generally fortuitous. Serum CA19-9 was elevated in half of the cases. No specific radiological feature was identified. Fine needle aspiration and cytologic analysis allowed a correct preoperative diagnosis in 21% of the patients, showing presence of squamous cells, lymphocytes, and keratinous debris. Half of them were treated conservatively, whereas other patients underwent surgery. Neither malignant transformation nor recurrence after resection was observed.

CONCLUSIONS

The LEC of the pancreas is a rare benign tumor that could be treated conservatively. Fine needle aspiration is the only tool that can achieve a diagnosis without resection. If no certain diagnosis can be made, surgery is warranted to rule out a malignant differential diagnosis.

Utilization of ancillary studies in the cytologic diagnosis of biliary and pancreatic lesions: The Papanicolaou Society of Cytopathology Guidelines

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound guided fine needle aspiration, terminology and nomenclature of pancreatobiliary disease, ancillary testing and post-biopsy management. All documents are based on the expertise of the authors, a review of the literature, discussion of the draft document at several national and international meetings and synthesis of selected online comments of the draft document. This document presents the results of these discussions regarding the use of ancillary testing in the cytologic diagnosis of biliary and pancreatic lesions. Currently, fluorescence in-situ hybridization (FISH) appears to be the most clinically relevant ancillary technique for cytology of bile duct strictures. The addition of FISH analysis to routine cytologic evaluation appears to yield the highest sensitivity without loss in specificity. Loss of immunohistochemical staining for the protein product of the SMAD4 gene and positive staining for mesothelin support a diagnosis of ductal adenocarcinoma. Immunohistochemical markers for endocrine and exocrine differentiation are sufficient for a diagnosis of endocrine and acinar tumors. Nuclear staining for beta-catenin supports a diagnosis of solid-pseudopapillary neoplasm. Cyst fluid analysis for amylase and carcinoembryonic antigen aids in the pre-operative classification of pancreatic cysts. A number of gene mutations (KRAS, GNAS, von Hippel-Lindau, RNF43 and CTNNB1) may be of aid in the diagnosis of cystic neoplasms. Other ancillary techniques do not appear to improve diagnostic sensitivity sufficiently to justify their increased costs.

Utilization of ancillary studies in the cytologic diagnosis of biliary and pancreatic lesions: the Papanicolaou Society of Cytopathology guidelines for pancreatobiliary cytology

The Papanicolaou Society of Cytopathology has developed a set of guidelines for pancreatobiliary cytology including indications for endoscopic ultrasound-guided fine-needle aspiration, terminology and nomenclature of pancreatobiliary disease, ancillary testing, and post-biopsy management. All documents are based on the expertise of the authors, a review of the literature, discussions of the draft document at several national and international meetings, and synthesis of selected online comments of the draft document. This document presents the results of these discussions regarding the use of ancillary testing in the cytologic diagnosis of biliary and pancreatic lesions. Currently, fluorescence in situ hybridization (FISH) appears to be the most clinically relevant ancillary technique for cytology of bile duct strictures. The addition of FISH analysis to routine cytologic evaluation appears to yield the highest sensitivity without loss in specificity. Loss of immunohistochemical staining for the protein product of the SMAD4 gene and positive staining for mesothelin support a diagnosis of ductal adenocarcinoma. Immunohistochemical markers for endocrine and exocrine differentiation are sufficient for a diagnosis of endocrine and acinar tumors. Nuclear staining for beta-catenin supports a diagnosis of solid-pseudopapilary neoplasm. Cyst fluid analysis for amylase and carcinoembryonic antigen aids in the preoperative classification of pancreatic cysts. Many gene mutations (KRAS, GNAS, VHL, RNF43, and CTNNB1) may be of aid in the diagnosis of cystic neoplasms. Other ancillary techniques do not appear to improve diagnostic sensitivity sufficiently to justify their increased costs.

Ancillary Studies, Including Immunohistochemistry and Molecular Studies, in Pancreatic Cytology

Fine-needle aspiration biopsy of the pancreas is indicated for sampling of solid and cystic masses. Preoperative cytologic diagnosis of pancreatic ductal adenocarcinoma and cystic lesions on cytology can be problematic, and ancillary studies may help confirm diagnosis. Ancillary studies in pancreatic cytology include special stains, immunohistochemistry, mutational analyses of specific genes, cyst fluid analysis of tumor markers and enzymes, and, in some instances, flow cytometry. Proteomics, microRNA sequencing, and whole-exome gene sequencing have been used to illustrate the progression of pancreatic neoplasms and identify key diagnostic markers. This article summarizes recent literature on ancillary studies in pancreatic fine-needle aspiration samples.

Primary pancreatic cystic neoplasms of the pancreas revisited. Part IV: rare cystic neoplasms

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.

Pancreatic Cystic Lesions of Nonmucinous Type

Cystic lesions of nonmucinous type can arise within the pancreas or can develop from adjacent structures and appear to involve the pancreas. In addition, some typically solid masses can become cystic or can present as cystic lesions. Nonmucinous cysts can be neoplastic, inflammatory, reactive, or congenital. The vast majority of neoplastic nonmucinous cysts are benign. Because of the difficulty in determining the neoplastic potential of a pancreatic cyst preoperatively, many non-neoplastic cysts are resected. This article reviews the surgical pathology of nonmucinous cysts.

Selected case from the Arkadi M. Rywlin International Pathology Slide Seminar: benign lymphoepithelial cyst, head of pancreas

Pancreatic lymphoepithelial cysts are more common in men, can occur anywhere in the pancreas, are sharply demarcated from surrounding tissues, and range in size from 1.2 to 17 cm. Patients are usually middle aged, presenting symptoms include abdominal pain, nausea, vomiting, and diarrhea, although many tumors are asymptomatic and are discovered incidentally on organ imaging or at autopsy. An elevated serum carbohydrate-associated antigen 19-9 may wrongly suggest a mucinous neoplasm. The diagnosis can be made preoperatively with a combination of organ imaging, fine needle aspiration biopsy, or ultrasound-guided Trucut biopsies. Cysts can be unilocular, bilocular, or multilocular, have walls up to 0.6 cm thick which are lined by squamous epithelium, occasional columnar mucinous cells, and small foci of sebaceous cells. The epithelium is surrounded by a dense rim of lymphoid tissue with scattered lymphoid follicles. Invaginations of the epithelium into the lymphoid tissue, reminiscent of a Warthin tumor, are occasionally observed. The pathogenesis is unknown. Pancreatic lymphoepithelial cysts are cured by conservative resection but if they are asymptomatic and are diagnosed before surgery, no treatment is necessary.

Lymphoepithelial cyst of the pancreas: a rare case report and review of literature

Lymphoepithelial cysts are rare pancreatic lesions of undetermined pathogenesis. The literature on this entity is limited to case reports or small series. We describe a case of 66 year male, incidentally diagnosed as lymphoepithelial cyst of pancreas that was managed by enucleation. This is the first case report of lymphoepithelial cyst from India. An extensive Medline search was carried out for lymphoepithelial cyst of pancreas. Till date less than 100 cases were identified in available literature. All these cases (including our case) were analyzed. This entity has uniform and distinctive clinicopathological features. About half of the reported cases were asymptomatic with most of the lesions diagnosed incidentally. Majority of patients presents with non-specific symptoms making preoperative diagnosis difficult. Lymphoepithelial cyst of the pancreas is a rare benign lesion, which is difficult to diagnose preoperatively. High index of suspicion and preoperative fine needle aspiration cytology may help in making diagnosis and avoiding surgery in asymptomatic patients.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s12262-010-0152-y) contains supplementary material, which is available to authorized users.

Pancreatic lymphoepithelial cysts express CEA and can contain mucous cells: potential pitfalls in the preoperative diagnosis

Pancreatic lymphoepithelial cysts are rare benign cysts that cannot be reliably differentiated from neoplastic mucinous cysts preoperatively. Although elevated cyst fluid carcinoembryonic antigen (CEA) levels support a diagnosis of a mucinous cyst, the finding of increased CEA levels in lymphoepithelial cysts prompted this study. Nine resected lymphoepithelial cysts were examined for expression of CEA, carbohydrate antigen (CA) 19-9, CK7, p63, PAS-D and a panel of mucins. The pathology data were correlated with clinical information, including serum, cyst fluid and imaging studies. By computed tomography scan, although most lymphoepithelial cysts appeared cystic, 23% were described as masses. The endoscopic ultrasound findings were variable, but the lymphoepithelial cysts tended to be hypoechoic cystic lesions or masses. On cytology, 44% of the cysts had squamous cells, 67% had glandular cells and 56% had atypical cells. The cysts were resected because of size ≥3 cm (89%), symptoms (44%) and/or elevated cyst fluid CEA levels (33%). The cyst fluid CEA levels in the three cysts tested were >450 ng/ml. Histopathologically, all cysts were lined by mature, stratified squamous-type cells and produced keratin. Mucous cells were present in 78% of the cysts. The immunohistochemical profile of the squamous lining was CK7+, p63+, MUC1+, MUC4+, MUC2-, MUC5AC- and MUC6-. Even though lymphoepithelial cysts are lined by squamous-type epithelium, all our resected lymphoepithelial cysts expressed CEA and/or CA19-9, many contained mucous cells, and three exhibited markedly elevated cyst fluid CEA levels. Although cyst fluid CEA levels >200 ng/ml support the diagnosis of mucinous neoplasms, this study emphasizes the need for clinicians and pathologists to recognize that lymphoepithelial cysts can mimic neoplastic mucinous cysts clinically, radiographically and on cyst fluid CEA analysis.

Pancreatic cytopathology: a practical approach and review

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.

Lymphoepithelial cysts of the pancreas: an EUS case series

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 cyst of the pancreas: report of a case

A lymphoepithelial cyst (LEC) is an extremely rare benign lesion of the pancreas. During a medical check-up, a 77-year-old man without any symptoms was found to have a cyst in the body of the pancreas. His serum carbohydrate antigen 19-9 level was slightly elevated. Computed tomography showed a multilocular, low-attenuating cyst on the superior surface of the pancreatic body. Thus, we performed distal pancreatectomy with splenectomy. Histological examination revealed that the cyst wall was lined with squamous epithelium and surrounded by abundant mature lymphoid tissue. Keratinous substances were present in the cyst. An LEC of the pancreas is associated with a good prognosis and, although unusual, it should be considered in the differential diagnosis of pancreatic cystic lesions. Minimal resection of the cyst should be performed whenever possible, and extensive surgery avoided. For patients with a high surgical risk, fine-needle aspiration biopsy may be considered.

Fine-needle aspiration cytology of pancreatic lymphoepithelial cysts

BACKGROUND

Lymphoepithelial cysts (LECs) of the pancreas are extremely rare, benign, nonneoplastic cysts that can mimic pseudocysts or cystic neoplasms clinically and radiographically. The cytologic features of LECs have been described only in a handful of case reports and may overlap with both benign and malignant pancreatic tumors.

METHODS

The authors conducted a 5-year, retrospective, computerized review of the cytopathology files of 2 institutions for all diagnoses of pancreatic LECs. Clinical, radiographic, cytologic, and chemical findings were reviewed.

RESULTS

Four patients were identified. The study group consisted of 3 men and 1 woman who ranged in age from 33 years to 63 years. The masses were located throughout the pancreas. Tumor sizes ranged from 1.8 cm to 5.7 cm in greatest dimension. Smears from all patients revealed numerous anucleated squamous cells, rare benign nucleated cells, amorphous debris, and an absence of lymphocytes. Mildly atypical mucinous glandular and parakeratotic epithelium were identified in 2 patients, leading to diagnoses of atypical and suspicious for malignancy. Subsequent surgical follow-up of 3 patients revealed pancreatic LECs.

CONCLUSIONS

Pancreatic LECs are extremely rare, and certain cytologic pitfalls may hinder a correct prospective diagnosis. Familiarity with the lesion's clinical and cytologic features may help clinicians arrive at the appropriate prospective diagnosis and, thus, permit conservative management. Cancer

Kyste lymphoépithélial inhabituel du pancréas. À propos d'un cas

Lymphoepithelial cyst of the pancreas is a benign and rare pathology. Its histogenesis is still unknown. The diagnosis is difficult to establish before surgery. We report a new case of a 20-year-old woman admitted for abdominal pain and vomiting. Radiologic investigations described a multilocular cystic tumor of the tail of the pancreas. The patient underwent a left pancreatectomy with splenectomy. Histologic investigations revealed pancreatic cysts lined by squamous epithelium surrounded by dense lymphoid tissue. The diagnosis of lymphoepithelial cyst of the pancreas was done.

Lymphoepithelial cysts of the pancreas: case report and review of the literature

The aim of this report was to describe the clinical and pathologic features of lymphoepithelial cysts of the pancreas, establish the differential diagnosis of other pancreatic cysts, and review the literature. A 53-year-old man was incidentally diagnosed with a pancreatic lesion after an abdominal CT scan. This study showed a solid mass in the tail of the pancreas not enhanced by helical CT. Endoscopic ultrasound examination revealed a low-density tissue mass on the surface of the pancreas, less echogenic than the surrounding parenchyma. Distal pancreatectomy and splenectomy were performed with a suspected diagnosis of mucinous cystic tumor. The patient has had an uneventful postoperative period, and the pathologic finding was a lymphoepithelial cyst of the pancreas. Lymphoepithelial cyst of the pancreas is an unusual and benign entity that must be taken into consideration when evaluating a cystic lesion of the pancreas because a different therapeutic approach may be required.

Lymphoepithelial cysts of the pancreas: a report of 12 cases and a review of the literature

Lymphoepithelial cyst (LEC) of the pancreas is a rare lesion of undetermined pathogenesis that had been documented almost exclusively in males. The literature on this entity is limited to reports of single or small numbers of cases. Here is presented a clinicopathologic analysis of 12 patients with LEC, 4 of whom were female. The mean age of the patients was 56 years. Four patients presented with abdominal pain and nausea, but in two patients, the cysts were detected incidentally. Only one patient had a history of chronic pancreatitis, and another had a family member with pancreatic cancer. In one patient, a clinical diagnosis of pseudocyst was rendered, and the remaining patients were clinically thought to have cystic neoplasms. None of the patients had any identifiable immunosuppression, HIV positivity, autoimmune disorder (such as Sjogren syndrome) or lymphoma. Seven cysts were located in the head of the pancreas, and 5 were in the tail. The mean size was 4.8 cm (range, 1.2-17 cm). Five LECs were multilocular, three were unilocular; in others, the number of loculi was not recorded. All were "macrocystic" lesions. Two patients had two separate lesions, both in the tail of the pancreas. Histologically, all cases were characterized by cysts, some containing keratin, and lined by mature stratified squamous epithelium surrounded by dense lymphoid tissue, often with prominent follicles. In some areas, the lining epithelium had more cuboidal, flattened, or transitional appearance. Mucinous goblet-like cells were seen in one case. Acute inflammation was not seen. Four cases contained solid lymphoepithelial islands, a feature not previously described in LECs. No squamous metaplasia was identified in the uninvolved pancreatic tissue and no epithelial elements were identified in peripancreatic lymph nodes. In summary, LEC of the pancreas is a rare but distinctive lesion that may be seen in the tail of the organ where most cystic pancreatic neoplasms are encountered. In contrast to the impression from the literature, LECs may also develop in females and, therefore, should be considered in the clinical differential diagnosis of mucinous cystic neoplasms that affect a similar age group. LECs are not associated with the clinical syndromes that are seen with their analogues in the salivary glands.