Lymphoepithelial cysts of the pancreas: CT and sonographic findings

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 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.

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.

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.

Imaging features of the less common pancreatic masses

Contrast-enhanced multiphase CT and dynamic gadolinium-enhanced MR have been validated in the literature as outstanding modalities for the evaluation of pancreatic pathology. In addition to the more frequently seen pancreatic adenocarcinoma, neuroendocrine tumors of the pancreas and cystic lesions such as serous and mucinous cystadenomas and IPMNs, a variety of benign and malignant lesions may occur in the pancreas. The purpose of this pictorial essay is to review the imaging findings of a variety of uncommon, benign and malignant, pancreatic neoplasms.

Lymphoepithelial cyst of the pancreas: comparison of CT findings with other pancreatic cystic lesions

OBJECTIVE

To describe the CT findings of lymphoepithelial cysts (LECs) of the pancreas and to investigate the differential findings between LECs and other pancreatic cystic lesions.

MATERIALS AND METHODS

Fifty-eight patients with 8 LECs (M:F = 7:1; mean age 55.1 years), 30 serous cystadenomas (SCA) (M:F = 11:19; 52.5 years), 11 mucinous cystadenomas (MCA) (M:F = 0:11; 47.2 years), and 9 pseudocysts (M:F = 6:3; 50.8 years) were included in this study. Two radiologists analyzed all CT images for 3D location, outer shape, appearance, the presence of calcification, enhancing nodule, and pancreatic duct dilatation. Size of lesions and CT number of cystic portion on precontrast CT were measured. For statistical analysis, Mann-Whitney U test and Fisher's exact test were used.

RESULTS

75 % (6/8) of LECs showed an extrapancreatic location than all other cystic diseases in terms of 3D location (p < 0.0001). LECs showed variable outer shape without a significant difference from that of SCAs and pseudocysts (p > 0.05), but LECs showed microlobulated surface more frequently than the MCAs (p < 0.05). LECs showed a variable appearance from unilocular to multi-microcystic. CT attenuation of LECs (21.2 ± 7.1 HU) was higher than that of SCAs and MCAs (p = 0.005). Size of LECs (34.0 ± 10.8 mm) was smaller than that of MCAs (p = 0.040). There was no calcification, pancreatic duct dilatation, or enhancing nodules in LECs.

CONCLUSION

LECs appear as a highly exophytic medium-sized cystic mass with various morphology occurring predominantly in the middle-aged or older male patients.

Lymphoepithelial cysts in the pancreas: MRI of two cases with emphasis of diffusion-weighted imaging characteristics

Pancreatic lymphoepithelial cysts (LECs) are rare pancreatic cystic lesions filled with keratinized material, lined by mature, keratinizing squamous epithelium and surrounded by lymphoid tissue containing few lymphoid follicles. We report two cases of surgically confirmed pancreatic LECs showing a profound restriction of water molecules on diffusion-weighted (DWI) magnetic resonance imaging (MRI). For pancreatic cystic lesions showing lack of molecular motion on DWI with or without thin marginal enhancement on contrast material-enhanced imaging, LECs consisting of internally keratinized materials with restricted diffusion should be considered in differential diagnoses even though they cannot always be easy to distinguish from other focal pancreatic lesions containing mucin, blood clot, or nonliquefactive necrosis.

Lymphoepithelial cyst of the pancreas that was difficult to distinguish from branch duct-type intraductal papillary mucinous neoplasm: report of a case

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.

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.

Macrocystic pancreatic lesions: differentiation of benign from premalignant and malignant cysts by CT

OBJECTIVE

To assess useful CT features for differentiating benign from premalignant and malignant macrocystic pancreatic lesions.

METHODS

Seventy-four patients with pathologically proven macrocystic pancreatic lesions were enrolled: 17 benign cysts (macrocystic serous cystadenoma, n=12; congenital cyst; n=5) and 57 premalignant and malignant cysts (mucinous cystic neoplasm, n=28; intraductal papillary mucinous neoplasm of branch duct type, n=20; tumor with cystic change, n=9). Size, location, shape (lobulated, round or oval, or complex cystic with tubular cyst), wall thickness (thin, < or =1mm; thick, >1mm), internal surface (smooth or irregular), and other findings were analyzed with multiphasic CT with thin-section (2.5-3mm) images. CT features between two groups were compared using univariate and multivariate stepwise logistic regression analyses.

RESULTS

On univariate analysis, the differences for the shape (p=0.007), wall thickness (p=0.011), and internal surface (p=0.012) between benign and premalignant and malignant cysts were significant. A lobulated shape, a thin wall and a smooth internal surface were more frequent in benign cysts, whereas a round or oval shape or a complex cystic shape with tubular cyst, a thick wall and an irregular internal surface were more frequent in premalignant and malignant cysts. On multivariate analysis, the shape (p=0.002) and wall thickness (p=0.025) were significant CT features for differentiating benign from premalignant and malignant cysts.

CONCLUSION

Shape and wall thickness are the main CT features for differentiating benign from premalignant and malignant macrocystic pancreatic lesions.

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.

Unusual cystic neoplasms in the pancreas: radiologic-pathologic correlation

Cystic neoplasms in the pancreas encompass a broad spectrum of benign, borderline, and malignant lesions that either are primarily cystic or result from the cystic degeneration of solid tumors. Although these lesions show different histologic findings, the overlap of the radiologic findings for many pancreatic cystic lesions makes differentiation difficult, and the clinical manifestations can also overlap. Therefore, some of the pancreatic cystic lesions, especially uncommon lesions, can cause diagnostic confusion, and this may result in unnecessary surgery or inappropriate follow-up. In this article, we discuss and illustrate the radiologic features of unusual cystic neoplasms and the unusual findings of the relatively common cystic neoplasms in the pancreas. We also correlate the radiologic findings with the findings on pathologic analysis.

Lymphoepithelial cyst of the pancreas—evaluation with multidetector CT

Lymphoepithelial cyst of the pancreas is a rare cystic pancreatic tumor. In this case report we provide the imaging perspective of the lesion including the role of multidetector CT (MDCT) and CT angiography and 3D imaging.

Le kyste lympho-épithélial du pancréas : à propos d’un cas

Lymphoepithelial cyst is a rare benign dysembryoplastic lesion of the pancreas, difficult to diagnose before surgery. The authors report the case of a 44 year old man with low left sided chest pain. CT-scan described a multilocular cystic tumor of the tail of the pancreas. The patient underwent a distal pancreatectomy with splenectomy. Histologic analysis led to the diagnosis of lymphoepithelial cyst of the pancreas. Through this observation, the authors stress the value of imaging in this benign entity that must be considered when evaluating a cystic pancreatic lesion because a different therapeutic approach may be required.

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.

Cytologic features of lymphoepithelial cyst of the pancreas: two preoperatively diagnosed cases based on fine-needle aspiration

We describe the cytologic features seen in fine-needle aspiration (FNA) specimens from two cases of preoperatively diagnosed lymphoepithelial cyst (LEC) of the pancreas. Pancreatic LEC is a rare, true cyst of uncertain histogenesis that may clinically and radiologically mimic a pseudocyst or cystic neoplasm. Both our patients were middle-aged men who presented with vague abdominal pain. Computed tomography (CT) of the abdomen revealed a mass in or around the pancreas, and CT-guided percutaneous FNA (patient 1) and endoscopic ultrasound-guided FNA (patient 2) yielded paste-like yellow-gray material. Cytologic smears showed numerous anucleated squamous cells in a background of keratinous and amorphous debris. A few benign nucleated squamous cells and plate-like cholesterol crystals were also seen. Unlike LEC of the head and neck region, only rare lymphocytes and histiocytes were present. Pancreatic LEC was diagnosed based on these cytologic findings and was histologically confirmed following cyst enucleation (patient 1) and partial pancreatectomy (patient 2). We conclude that preoperative FNA and recognition of the characteristic cytologic pattern will enable conservative surgical management of pancreatic LEC. Diagn. Cytopathol. 1999;21:346-350.

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

Most pancreatic cysts (90%) are inflammatory pseudocysts. Approximately 10% of pancreatic cysts are neoplasms, including serous cystadenomas, and mucinous tumors, some of which are malignant. Analysis of pancreatic cyst fluid obtained by percutaneous or endoscopic fine-needle aspiration is increasingly being used for the preoperative diagnosis of pancreatic or peripancreatic cysts. However, cyst fluid chemical and cytologic features in less common types of pancreatic cysts have not been reported. Lymphoepithelial cyst of the pancreas is exceedingly rare, and only occasional individual reports have described cyst fluid findings. We report on a case of lymphoepithelial cyst of the pancreas developing in a middle-aged man. Cyst fluid aspirated under radiological guidance showed elevated levels of carcinoembryonic antigen (CEA), CA19-9, CA 125, and amylase, and a viscosity greater than that of serum. A cell block preparation of a fine-needle aspiration showed tissue fragments with a keratinized squamous lining and a lymphocytic infiltrate in the wall, and abundant background keratinous debris. The cytologic and biochemical findings in this case exhibit similarities to the findings reported in other reports, and may represent a recognizable pattern on cyst fluid analysis.