Lymphoepithelial cyst of the pancreas: an analysis of 117 patients

Misdiagnosis of pancreatic intraductal papillary mucinous neoplasms and the challenge of mimicking lesions: imaging diagnosis and differentiation strategies

The rising prevalence of pancreatic cystic lesions (PCLs), particularly intraductal papillary neoplasms (IPMNs), has been attributed to increased utilization of advanced imaging techniques. Incidental detection of PCLs is frequent in abdominal CT and MRI scans, with IPMNs representing a significant portion of these lesions. Surveillance of IPMNs is recommended due to their malignant potential; however, their overlapping imaging features with benign entities can lead to misdiagnosis, overtreatment, and overutilization of healthcare resources. This paper aims to highlight and differentiate lesions often mistaken for IPMNs, providing insight into their imaging characteristics, diagnostic challenges, and distinctive features while highlighting the incidence of wrong diagnosis for these lesions. These lesions include serous cystadenomas, cystic pancreatic neuroendocrine tumors, mucinous cystic neoplasms, lymphoepithelial cysts, duodenal diverticula, pancreatic schwannomas, chronic pancreatitis, retention cysts, intrapancreatic accessory spleens, pancreatic lipomas, choledochal cysts, and others. Utilizing various imaging modalities, including contrast-enhanced CT, MRI, and EUS, alongside histological and molecular analyses, can aid in accurate diagnosis and appropriate management. Understanding these mimicry scenarios is crucial to avoid unnecessary surveillance, interventions, and the burden they place on both patients and healthcare systems. Improved recognition of these lesions can lead to better patient outcomes and resource allocation.

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

BACKGROUND

Lymphoepithelial cysts (LECs) of the pancreas are a rare type of true pancreatic cysts and represent an estimated 0.5% of all pancreatic cystic lesions. They are benign lesions and have no malignant potential. However, they are hard to differentiate from malignant lesions because their imaging and clinical presentation vary greatly. Seeing as these are benign lesions which are increasingly found incidentally during imaging for other indications, correct diagnosis is important to prevent unnecessary intervention and morbidity.

CASE REPORT

We report the case of a 41-year-old female who presented with abdominal discomfort, bloating and dyspepsia. An abdominal computed tomography (CT) showed a large mass in the left fossa. We describe the diagnostic and therapeutic measures taken in this case.

METHODS

We reviewed the literature for common features of the LEC. We grouped common imaging and histological features of the LEC of the pancreas to provide easily identifiable characteristics to facilitate diagnosis. For the review, we focused on papers, mostly case reports, presenting these common characteristics. We also reviewed the literature for key topics that should be taken into account when considering therapeutic interventions in a patient with a possible diagnosis of a LEC.

CONCLUSION

Cysts of the pancreas are increasingly identified due to widespread use and improved resolution of cross-sectional imaging. To obtain the correct diagnosis, it is sometimes necessary to combine advanced imaging, i.e. CT and MRI-imaging, and endoscopic ultrasound with fine needle aspiration (EUS/FNA), while CA 19-9 also has diagnostic value. We summarize all diagnostic characteristics in a table for ease of use. Furthermore we summarized possible therapeutic interventions.

Lymphoepithelial cyst of the pancreas: can common imaging features help to avoid resection?

BACKGROUND

Differentiation of cystic pancreatic neoplasms remains a challenging task for radiologists regarding the main aim of identifying malignant and premalignant lesions.

PURPOSE

The study aimed to compare the radiological features of lymphoepithelial cysts (LEC) with other cystic pancreatic lesions, which could help to differentiate them in order to avoid unnecessary resection.

MATERIAL AND METHODS

We retrospectively reviewed 10 cases of resected and histopathologically confirmed LECs during a 12-year period with available imaging studies; 20 patients with mucinous cystic neoplasms (MCN), 20 patients with branch-duct intraductal papillary mucinous neoplasms (BD-IPMN), and 20 patients with serous cystic neoplasms (SCN) were selected to serve as control groups. Imaging findings as well as clinical data were analyzed.

RESULTS

The following imaging morphology of LEC was identified: simple cystic appearance (20%) and mixed cystic-solid appearance (80%) with either a diffuse subsolid component (30%) or mural nodule(s) (50%). All lesions revealed exophytic location with a strong male predominance (9:1). MCNs occurred exclusively in middle-aged women, IPMN in both sexes showed slight male predominance (13:7), and SCN showed female predominance (5:15). Median patient age in LEC (48.5, IQR 47-54.5) was significantly younger compared to IPMN (p < 0.001) and SCN (p = 0.02). Unenhanced CT attenuation of LEC was higher than MCNs (p = 0.025) and IPMNs (p = 0.021), showing no significant difference to SCN (p = 0.343).

CONCLUSION

The present study provides key radiological features of LEC for the differentiation from other cystic pancreatic lesions such as increased CT attenuation in the unenhanced phase, absence of a connection to the main pancreatic duct (MPD), and exophytic location. In addition to these imaging features, clinical data, such as male predominance in LEC, must be considered for the differentiation of cystic pancreatic lesions.

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.

Exophytic pancreatic lymphoepithelial cyst incidentally detected in a differentiated thyroid cancer patient on whole-body I-131 scan: a case report

Background

Radioiodine (I-131) whole-body scintigraphy (WBS) is a useful modality for identifying functionally preserved thyroid tissue and metastases from differentiated thyroid cancer (DTC); however, the specificity of I-131 uptake is limited, and its accumulation in the pancreas has not been well described.

Case presentation

A 70-year-old male patient with DTC who had previously undergone total thyroidectomy (pT3N1bM0 Stage IV) received radioiodine treatment at our facility. After treatment, an I-131 WBS revealed abnormal I-131 uptake in the head of the pancreas. Computed tomography identified a round hypodense mass (10 × 20 mm) adjacent to the pancreas head that was impervious to fluorodeoxyglucose (¹⁸F-FDG) during subsequent ¹⁸F-FDG-positron emission tomography. A diagnosis of pancreatic metastasis from the DTC could not be excluded; therefore, local resection was performed for diagnostic certainty and treatment. Histopathology confirmed the mass to be an exophytic lymphoepithelial cyst (LEC) of the pancreas. The patient also had a transient pancreatic leak which spontaneously resolved after surgery, and he was discharged from the hospital on postoperative day 8.

Conclusion

To the best of our knowledge, this is the first reported case of an exophytic pancreatic LEC producing a false-positive result during I-131 WBS. Knowledge of all potential I-131 false-positive findings may help improve the management of patients with DTC and circumvent misdiagnoses.

A lymphoepithelial cyst in the pancreatic accessory spleen: A case report

We present the first report of a lymphoepithelial cyst. As additional cases will likely be encountered in the future, our study sets the precedent for future research.

Lymphoepithelial cyst mimicking pancreatic cancer: a case report and literature review

Background

Pancreatic lymphoepithelial cyst (LEC) is a rare nonmalignant cyst consisting of a benign collection of keratinizing squamous epithelial cells with lymphoid tissue. Diagnosing LEC preoperatively is considered difficult because of its non-specific clinical features; therefore, LEC is generally treated the same as a malignant tumor.

Case presentation

Our case was a 65-year-old man who underwent pancreatoduodenectomy 3 years previously for carcinoma arising from the ampulla of Vater. A pancreatic mass in the remnant pancreatic tail was detected through follow-up abdominal contrast-enhanced computed tomography (CT). This revealed two adjacent ring-enhanced masses that had been in tight contact with the left diaphragm and were enlarged. The tumors had high signal intensity in diffusion-weighted images of magnetic resonance imaging, and fluorodeoxyglucose-positron emission tomography (FDG-PET) showed abnormal uptake (standardized uptake value maximum: 17.4). Therefore, we conducted a partial resection of the remnant pancreas with concomitant resection of the left diaphragm. Microscopically, one of the tumors revealed rare fragments of apparently benign squamous epithelium on a background of keratinous debris, cyst contents, and scattered lymphocytes, and the adjacent mass revealed infiltrated neutrophils. The histopathological diagnosis was an LEC with chronic abscess. The patient recovered uneventfully and was discharged on postoperative day 10.

Conclusions

We reported a rare case of LEC with chronic abscess that was positively visualized on FDG-PET. When a pancreatic malignancy cannot be excluded, surgical resection is considered inevitable.

Imaging features and pathological evaluation by EUS-FNA enable conservative management in patient of lymphoepithelial cyst of the pancreas: a case report

Pancreatic lymphoepithelial cysts (LECs) are rare cystic lesions filled with a keratinous substance and lined by squamous epithelium with underlying lymphoid tissue. Because pancreatic LECs are entirely benign, correct preoperative diagnosis is important to avoid unnecessary surgery. However, the imaging features of pancreatic LECs are not specific and preoperative diagnosis has proven difficult. A pancreatic mass was incidentally detected through abdominal ultrasonography in a 63-year-old male presenting without any symptoms. Computed tomography showed an exophytic cystic lesion in the pancreatic head. The lesion had heterogeneous high signal intensity with partial low intensity on T2-weighted magnetic resonance imaging (MRI) and high signal intensity on diffusion MRI. Endoscopic ultrasound (EUS) examination showed an encapsulated cystic lesion with relatively homogenous and highly echoic contents. EUS-guided fine-needle aspiration (EUS-FNA) revealed caseous appearance and rare fragments of apparently benign squamous epithelium on a background of keratinous debris, cyst contents, and scattered lymphocytes. We diagnosed a pancreatic LEC and opted for conservative management without surgery. Pathological evaluation based on images obtained through EUS-FNA showed macro- and microscopic features that were critical to determining the management strategy. In conclusion, the imaging and pathological features of pancreatic LECs can inform preoperative diagnosis, which may enable conservative management.

Lymphoepithelial cyst of the pancreas: A challenging diagnosis on fine needle aspiration

Lymphoepithelial cysts (LECs) of the pancreas are rare, benign pancreatic cysts comprising approximately 0.5% of all pancreatic cysts. They occur predominantly in men in the 5th and 6th decades of life. LECs are true cysts lined by stratified squamous epithelium with adjacent subepithelial lymphoid tissue. They range in size from 1.2 to 17 cm (mean size 4.6 cm) and can arise in any part of the pancreas. 1 LEC resembles other benign and malignant pancreatic cysts clinically and radiologically. The cytomorphologic features of LECs have been described in a small number of case reports and it has been indicated that features may overlap with other benign and malignant pancreatic lesions. Herein, we report clinical, radiological, cytological and histopathological features of a pancreatic LEC in a 62-year-old male.

A Rare Presentation of Pancreatic Lymphoepithelial Cyst: A Case Report and Review

Pancreatic lymphoepithelial cyst (LEC) is a rare, benign collection of keratinizing squamous epithelial cells encapsulated by lymphoid tissue. Because of its limited data and nonspecific features that can mimic malignant lesions, LECs can lead to unnecessary operations. A 62-year-old male with a known pancreatic mass presented with abdominal pain. CT scan showed an increased mass in the pancreatic head, and endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) revealed “rare fragments of benign-appearing squamous epithelium in a background of keratin debris, cyst contents, and scattered lymphocytes,” consistent with a lymphoepithelial cyst. Pancreatic LEC is an extremely rare lesion that comprises of only 0.5% of all pancreatic cysts. EUS-FNA has become the mainstay for diagnosing pancreatic LECs. Given the slow growing and benign nature, conservative management and observation is adequate for pancreatic LECs with excellent long-term outcome. With increasing number of imaging ordered by clinicians, it is anticipated that there will be a greater number of incidental pancreatic LECs detected. Thus, EUS-FNA should be utilized more frequently to help distinguish benign pancreatic LECs from premalignant or malignant lesions to avoid surgery.

Lymphoepithelial pancreatic cyst: A rare entity among pancreatic cystic lesions. Report of two cases

Lymphoepithelial pancreatic cysts are extremely rare benign pancreatic cystic lesions. High suspicion and an individual approach are imperative for the best management of those extremely rare entities.

Clinicopathological and immunohistochemical features of the oral lymphoepithelial cyst: A multicenter study

BACKGROUND

Analyze the clinical, demographic, histopathological, and immunohistochemical features of oral lymphoepithelial cyst (OLEC).

METHODS

Samples were retrospectively retrieved from five oral pathology services. Clinical and demographic data were collected from patient charts. Histopathological and immunohistochemical (CD3 and CD20) features were evaluated. Data analysis involved descriptive statistics and bivariate analyses (P ≤ .05).

RESULTS

Seventy-seven cases were found among a total of 146 150 specimens (0.05%). OLEC was predominantly diagnosed in females (70.1%). Mean patient age was 46.51 years. The lesions arose mainly on the lateral border of the tongue (40.3%), measured up to 1 cm (61.0%), and were asymptomatic (64.9%). Twenty-four lesions (31.2%) were white. Forty-one cases (53.2%) presented lymphocytic inflammatory infiltrate with no specific arrangement. The cystic lining was composed of a non-keratinized stratified epithelium (59.7%) presenting hyperplasia (39.0%). Connection with the surface, epithelium was found in 23 cases (29.9%) and 31 (40.3%) cases had two or more cystic cavities. The lumen content was predominantly desquamated cells (48.1%). Subgemmal neurogenous plaque was found in 11/42 (26.2%) cases involving the tongue. CD20⁺ cells predominated in 36/63 cases (57.2%), and lymphocytic inflammatory infiltrate was not always continuous around the cystic cavity (52.4%).

CONCLUSION

Lymphoepithelial cyst is an uncommon lesion of the oral cavity. The present study offers the largest sample of OLEC for which clinical, demographic, histopathological, and immunohistochemical features were evaluated. The clinical and demographic findings were similar to those described in previous reports, but the microscopic analyses revealed interesting aspects of the cystic epithelium and the lymphocytic inflammatory infiltrate in OLEC.

Lymphoepithelial cyst of the pancreas: A case report and summary of imaging features of pancreatic cysts

•

A lymphoepithelial cyst (LEC) of the pancreas is a benign and rare lesion.

•

A pancreatic LEC is difficult to be diagnosed and differentiate from the malignancy preoperatively.

•

We summarized the imaging features of pancreatic cysts to differentiate from the malignancy.

Introduction

A lymphoepithelial cyst (LEC) of the pancreas is a benign and rare lesion that is difficult to diagnose preoperatively based on imaging studies.

Presentation of case

We report a case of a 49-year-old man who presented with weight loss and diarrhea. The serum carcinoembryonic antigen and carbohydrate antigen 19-9 levels were slightly elevated to 6.7 ng/mL (reference value <5.0 ng/mL) and 45 U/mL (reference value <37 U/mL), respectively. Computed tomography showed a large cystic mass with internal septa in the pancreatic tail. The cystic wall and the septa showed enhancement while the cystic contents remained unenhanced. Magnetic resonance imaging (MRI) demonstrated a multiple-ball-like lesion with low signal intensity on T1-weighted image and high signal intensity on T2-weighted image. Diffusion-weighted MRI showed high signal intensity in the central and iso-signal intensity in the peripheral portions of the cystic lesion. The cystic wall and septa showed high signal intensity, and the cystic contents showed low signal intensity on an enhanced MRI. Endoscopic ultrasonography showed a cyst with multiple high-echoic lesions in the pancreatic tail. A mucinous cystic neoplasm and branch duct intraductal papillary mucinous neoplasm were considered among the differential diagnoses, and we performed distal pancreatectomy with concomitant splenectomy and lymphadenectomy for both diagnostic and therapeutic purposes. Histopathological findings revealed that the cystic wall was lined by stratified squamous epithelium, and several lymphoid follicles and a few sebaceous glands were observed within the cystic wall without hair follicles, leading to the final diagnosis of an LEC.

Conclusion

We report a rare case of a pancreatic LEC, which was difficult to be diagnosed and summarize the imaging features of pancreatic cysts to differentiate from the malignancy preoperatively.

Pancreatic Cytology

The diagnostic approach to pancreaticobiliary disease requires a multidisciplinary team in which the cytopathologist plays a crucial role. Fine-needle aspiration, obtained by endoscopic ultrasound, is the diagnostic test of choice for pancreatic lesions. Preoperative clinical management depends on many factors, many of which rely on accurate cytologic assessment. Pancreaticobiliary cytology is wrought with diagnostic pitfalls. Clinical history, imaging studies, cytology samples, and ancillary tests, including immunohistochemistry, biochemical analysis, and genetic sequencing, are integral to forming a complete diagnosis and guiding optimal patient management. This article reviews clinical aspects and the diagnostic work-up of commonly encountered diagnostic entities within the field of pancreatic cytology.

Lessons learned from 29 lymphoepithelial cysts of the pancreas: institutional experience and review of the literature

BACKGROUND

Lymphoepithelial cysts (LECs) are rare pancreatic cystic lesions. Since LECs are benign, preoperative diagnosis is important to differentiate from a cystic neoplasm and avoid unnecessary surgery. The aim of this study was to identify clinical, radiographic and cytopathologic features associated with LECs.

METHODS

A retrospective review was performed of patients diagnosed with LEC between 1995 and 2017 at our hospital. Clinicopathologic and radiographic imaging features were documented.

RESULTS

Of 29 patients with pancreatic LEC, 22 underwent surgical resection. The majority were male (n = 24) with a median age of 55 years (range, 21-74). During the evaluation, all patients underwent a CT, with endoscopic ultrasound (EUS) guided fine needle aspiration (FNA) biopsy (n = 22) and/or MRI/MRCP (n = 11) performed in a smaller number of patients. A combination of exophytic tumor growth on imaging and the presence of specific cytomorphologic features on the EUS-FNA cytology biopsy led to the correct diagnosis of LEC and prevention of unnecessary surgery in 7 patients.

DISCUSSION

Differentiating LECs from premalignant pancreatic cystic neoplasms remains difficult. Findings of an exophytic growth pattern of the lesion on abdominal imaging and the presence of specific cytomorphologic features in the EUS-FNA biopsy could help clinicians diagnose LEC preoperatively.

Benign Tumors and Tumorlike Lesions of the Pancreas

The pancreas is a complex organ that may give rise to large number of neoplasms and non-neoplastic lesions. This article focuses on benign neoplasms, such as serous neoplasms, and tumorlike (pseudotumoral) lesions that may be mistaken for neoplasm not only by clinicians and radiologists, but also by pathologists. The family of pancreatic pseudotumors, by a loosely defined conception of that term, includes a variety of lesions including heterotopia, hamartoma, and lipomatous pseudohypertrophy. Autoimmune pancreatitis and paraduodenal ("groove") pancreatitis may also lead to pseudotumor formation. Knowledge of these entities will help in making an accurate diagnosis.

Pancreatic Lymphoepithelial Cysts Diagnosed with Endosonography-guided Fine Needle Aspiration

Although lymphoepithelial cysts (LECs) of the pancreas are benign lesions, most of them have been treated with surgical resection due to diagnostic difficulty. We report a 66-year-old woman diagnosed with pancreatic LECs. Abdominal ultrasound revealed two masses in the pancreas, which were not visible on the abdominal computed tomography. In an abdominal magnetic resonance imaging, pancreas lesions showed solid tumors, which revealed a low signal intensity on T1-, moderate high signal intensity on T2 weighted images, and homogeneous delayed enhancement in the portal venous phase. Endosonography (EUS) revealed two hypoechoic round masses measuring 1.5 cm and 4.5 cm in the body and tail of the pancreas, respectively. EUS-guided fine needle aspiration (FNA) revealed squamous cells, amorphous keratinous debris, and lymphocytes. The patient was diagnosed with LECs of the pancreas. For the duration of the follow-up period of two years, imaging studies were unchanged. EUS-FNA is useful in making a definite diagnosis and avoiding unnecessary surgery. This is the first case of pancreatic LECs diagnosed with EUS-FNA in Korea.

Calcified pancreatic and peripancreatic neoplasms: spectrum of pathologies

A variety of pancreatic and peripancreatic neoplasms may contain calcifications. We present a review of common to uncommon pancreatic neoplasms that may contain calcifications to include ductal adenocarcinoma, pancreatic neuroendocrine tumors, serous cystadenomas, solid pseudopapillary tumors, intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, and lymphoepithelial cysts. In addition, duodenal mucinous adenocarcinoma can present as a peripancreatic mass that may contain calcification. Knowledge of the spectrum of calcification patterns can help the interpreting radiologist provide a meaningful differential.

Oral lymphoepithelial cyst: A clinicopathological study of 26 cases and review of the literature

Introduction

Τo describe the clinicopathological features of 26 oral lymphoepithelial cysts (LECs) and review the literature.

Material and Methods

Twenty-six cases of oral LECs diagnosed during a 37-year period were retrospectively collected. The patients’ gender and age, as well as the main clinical features of the cysts were retrieved from the requisition forms. The main microscopic features were recorded after reevaluation of all cases. Pubmed and Google Scholar electronic databases were searched with the key word “oral LEC”. Inclusion criteria were the microscopic confirmation of LEC diagnosis and the report at least two of three main clinical features (gender, age and cyst’s location).

Results

The 26 oral LECs represented 0.08% of 31,564 biopsies accessioned during the study period. They affected 25 patients, 14 females and 11 males with a mean age of 33.04±9.81 years. They appeared as smooth (92%) nodules, with soft (24%) or firm (76%) consistency and normal (28%), yellow to normal (20%), yellow (32%) or white (20%) hue, in the tongue (69.23%) or the floor of mouth (30.77%). They were covered by parakeratinized squamous (92.31%) or non-keratinized (7.69%) epithelium and contained desquamated epithelial cells, amorphous eosinophilic material and/or inflammatory cells (100%). The lymphoid tissue surrounded the cystic cavity partially (34.62%) or completely (65.38%), often in a follicular pattern with prominent germinal centers (53.85%). Literature review yielded 316 cases of oral LECs derived from 25 case reports, 3 case studies/retrospective studies with detailed information for each case and 7 studies with summarized data.

Conclusions

Oral LEC is a pathologic entity with discrete clinical presentation that is, however, commonly misdiagnosed in clinical practice as other, mostly benign, entities. Its pathogenesis remains obscure, as its clinicopathologic features are consistent with both theories suggested up to date.

Key words:Oral lymphoepithelial cyst; developmental cyst; non odontogenic cyst; lymphoid tissue; oral tonsil.

Lymphoepithelial cyst of pancreas: spectrum of radiological findings with pathologic correlation

PURPOSE

The purpose of the study was to investigate imaging features as well as pathologic and clinical findings of lymphoepithelial cyst (LEC) of pancreas.

MATERIALS AND METHODS

Ten patients with surgically resected and pathologically proven LEC, found in a single institution database between 2000 and 2015, were evaluated in a retrospective fashion. Patients' demographics, clinical presentation, co-morbidities, imaging features, cytology and histopathology results, and serum/aspirate biomarkers levels were recorded.

RESULTS

Eighty percent of patients were male with median age of 59. All lesions were exophytic, with median size of 36 mm. 80% were classified as complex cystic lesions, showing enhancing septa or enhancing rim without measurable enhancing solid component. 80% were located in tail or body. In one patient with MRI, the lesion was mildly T1 hyperintense and markedly T2 hyperintense. All cases were anechoic or hypoechoic on EUS, and majority of them showed posterior acoustic enhancement. Of patients with available fluid aspirate analysis, 3 out of 4 had CEA level > 192 ng/mL and 1 out of 3 had elevated (>250 IU/ml) amylase level. Four out of 7 patients had elevated serum CA 19-9 levels (>37 U/mL); one patient with a value of 361 U/mL had co-existing pancreatic adenocarcinoma.

CONCLUSION

Round shape, mild complexity, and exophytic location in pancreatic body and tail can be suggestive of LECs. These features however are not specific and may be seen with other cystic pancreatic lesions. CT findings should be used in conjunction with EUS, cytology, and tumor marker studies to secure the diagnosis of LEC.

An Unusual Suspect: Lymphoepithelial Cyst of the Pancreas

Lymphoepithelial cysts (LECs) of the pancreas are benign, rare pancreatic cysts that are found predominantly in men. These cysts can present as a diagnostic conundrum given their rarity and difficulty of distinguishing these cysts from those with malignant potential. We present an incidental case of a LEC in a middle-aged man.

Lymphoepithelial cyst with sebaceous glands of the pancreas: a case report

Background

Lymphoepithelial cyst (LEC) of the pancreas is a rare benign tumor. LEC with sebaceous glands of the pancreas is extremely rare, and its histogenesis remains unclear.

Case presentation

We present a 66-year-old man with an incidental finding of a cystic lesion at the neck of the pancreas. Pancreatic juice cytology results and elevated serum carbohydrate antigen 19-9 and Dupan-2 levels indicated that the cyst was a potential adenocarcinoma. Therefore, a pancreaticoduodenectomy was performed. Macroscopically, the tumor was a unilocular cyst with a thin transparent wall, filled with soft yellow material. Pathological findings showed that the cyst was lined with squamous epithelium, accompanied by dense lymphoid tissue with scattered germinal centers. There were no hair follicles, but sebaceous glands were present in the lymphoid tissue just beneath the squamous epithelium. Therefore, the histopathological diagnosis was an LEC with sebaceous glands of the pancreas. Furthermore, the squamous epithelium surrounding the cyst was pathologically continuous with the tubular structure, indicating that the tubular structure transitioned into the squamous epithelium.

Conclusions

We report an extremely rare case of LEC with sebaceous glands of the pancreas. Moreover, the pathological findings, which showed that the tubular structure transitioned into the squamous epithelium, suggested that this was squamous metaplasia. In order to investigate the histogenesis of LEC of the pancreas, the pathological findings must be evaluated.

Morphological differentiation and follow-up of pancreatic cystic neoplasms using endoscopic ultrasound

Endoscopic ultrasound (EUS) is a key modality for the evaluation of suspected pancreatic cystic neoplasms (PCNs), as the entire pancreatic gland can be demonstrated with high spatial resolution from the stomach and duodenum. Detailed information can be acquired about the internal contents of the cyst(s) [septum, capsule, mural nodules (MNs)], its relation with the main pancreatic duct (MPD), and any parenchymal changes in the underlying gland. PCNs comprise true cysts and pseudocysts. True cysts can be neoplastic or nonneoplastic. Here, we describe serous cystic neoplasm (SCN), mucinous cystic neoplasm (MCN), and intraductal papillary mucinous neoplasm (IPMN) as prototype neoplastic cysts, along with nonneoplastic lymphoepithelial cysts (LECs).

Differential Diagnosis of Cystic Pancreatic Lesions Including the Usefulness of Biomarkers

Background

Cystic pancreatic lesions are more and more often found. Malignant risk ranges from nil to more than 60%. A precise diagnosis is required to adapt surveillance or therapeutic strategy.

Methods

We tried to identify the most difficult differential diagnoses encountered in a tertiary center of pancreatology and to guide the reader as how to reach the correct strategy and diagnosis in these situations.

Results

We identified eight clinically difficult situations: i) chronic pancreatitis versus intraductal papillary mucinous neoplasms, ii) serous versus mucinous cystic neoplasms, iii) serous cystic neoplasms versus branch-duct intraductal papillary mucinous neoplasms, iv) intraductal papillary mucinous neoplasms versus acinar cell cystadenoma, v) (pseudo-) solid serous cystic neoplasm versus neuroendocrine tumor, vi) pancreatic neuroendocrine tumors versus solid pseudopapillary tumors, vii) cystic forms of a solid tumor, and viii) rare pancreatic or peripancreatic cystic lesions. The work-up should rely on computed tomography scan, pancreatic magnetic resonance imaging, and, only if necessary, endoscopic ultrasound with or without fine needle aspiration.

Conclusion

An expert analysis of imaging data allows a precise diagnosis in most of the cases. Pancreatic resection should no longer be performed in case of diagnostic doubt.

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.

Rare nonneoplastic cysts of pancreas

Pancreatic cysts represent a small proportion of pancreatic diseases, but their incidence has been recently increasing. Most pancreatic cysts are identified incidentally, causing a dilemma for both clinicians and patients. In contrast to ductal adenocarcinoma, neoplastic pancreatic cysts may be cured by resection. In general, pancreatic cysts are classified as neoplastic or non-neoplastic cysts. The predominant types of neoplastic cysts include intraductal papillary mucinous neoplasms, mucinous cystic neoplasms, serous cystic neoplasms, and solid pseudopapillary neoplasms. With the exception of serous type, neoplastic cysts, have malignant potential, and in most cases requires resection. Non-neoplastic cysts include pseudocyst, retention cyst, benign epithelial cysts, lymphoepithelial cysts, squamous lined cysts (dermoid cyst and epidermal cyst in intrapancreatic accessory spleen), mucinous nonneoplastic cysts, and lymphangiomas. The incidence of nonneoplastic, noninflammatory cysts is about 6.3% of all pancreatic cysts. Despite the use of high-resolution imaging technologies and cytologic tissue acquisition with endosonography, distinguishing nonneoplastic from neoplastic cysts remains difficult with most differentiations made postoperatively. Nonetheless, the definitive distinction between non-neoplastic and neoplastic cysts is crucial as unnecessary surgery could be avoided with proper diagnosis. Therefore, consideration of these rare disease entities should be entertained before deciding on surgery.