Lymphoepithelial cyst of the pancreas

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.

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.

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.

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.

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

Imaging of cystic diseases of the pancreas

Although the majority of cystic lesions of the pancreas seen in clinical practice represent postinflammatory pseudocysts, it is important for the radiologist to be knowledgeable of the wide spectrum of cystic masses of the pancreas and the variable prognoses they possess. As a result of similarities in the imaging features of these lesions, a definitive diagnosis is often not possible. By combining imaging features with clinical history, a reasonable differential diagnosis can be offered to the referring physician. In some cases, biopsy or fluid aspiration may be required prior to surgery. In a patient without the appropriate history of pancreatitis and the presence of a cystic pancreatic mass, it is incumbent upon the radiologist to offer alternative diagnoses of cystic neoplasms of the pancreas.

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.

Characterization of cystic tumors of the pancreas: CT accuracy

PURPOSE

The purpose of this work was to evaluate the capabilities of CT to accurately characterize cystic tumors of the pancreas.

METHOD

Two observers retrospectively evaluated the CT exams of 100 cystic masses of the pancreas, with pathological confirmation. The two observers, blinded about clinical information and the final diagnosis, tried to categorize the lesions according to well established morphologic features. Statistical analysis was performed to measure the agreement between each radiologist and the consensus diagnosis and to evaluate the usefulness of certain CT findings in differentiating one type of cystic pancreatic neoplasm from another.

RESULTS

Serous cystadenoma was better diagnosed by CT [Youden misclassification index (Ymi) = 0.72] than mucinous cystic tumor (Ymi = 0.44) and solid pseudopapillary tumor (cystic variant) (Ymi = 0.47).

CONCLUSION

As patients with previous history of pancreatitis were excluded from the study, CT findings allowed correct characterization of only 60% of cystic pancreatic masses. Among the remaining 40%, 15-20% of the wrong diagnoses could not be corrected by means of CT, given the patterns shown by the tumors. In 20-25% of the cases, a nonspecific diagnosis of cystic mass was made.

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.

Lymphoepithelial cyst (LEC) of the pancreas: cytomorphology and differential diagnosis on fine-needle aspiration (FNA)

Lymphoepithelial cyst (LEC) of the pancreas is an extremely rare benign entity. We describe the cytopathologic findings of such a lesion in a 49-yr-old woman who was examined for epigastric pain. A trans-esophageal ultrasound-guided fine-needle aspiration of a pancreatic mass disclosed an intimate mixture of squamous epithelial cells and small, mature lymphocytes in a background of keratinaceous debris, anucleate squames, and multinucleated histiocytes. On histopathologic examination, a subsequent resection showed a multiloculated cystic lesion with a stratified squamous epithelial lining surrounded by well-formed lymphoid tissue, suggestive of LEC. The differential diagnosis includes other pancreatic pseudocysts, dermoid cyst, mucinous cystic neoplasms, adenosquamous carcinoma, and metastatic squamous cell carcinoma.

Cystic lymphoepithelial lesions of the pancreas and peripancreatic region: report of two cases

Two cases of an extremely rare cystic lymphoepithelial lesion of a lymph node associated with the pancreas are presented herein. The first patient was a 57-year-old woman with a serous cystoadenoma who underwent resection of the body and tail of pancreas, and the other patient was a 75-year-old woman with cancer of the papilla of Vater who underwent pylorus-preserving pancreatoduodenectomy. Both lesions were incidentally found during pathologic examination of lymph nodes from the peripancreatic region. Histologically, there were many scattered nests of the lymphoepithelial lesion in the lymphoid stroma, each of which was lined with stratified squamous epithelium. The pathological structure was found to resemble the lymphoepithelial lesion of the pancreas. Although the histogenesis is unknown, we hypothesize that the lesion might have arisen from squamous metaplasia of a benign epithelial inclusion such as the pancreatic duct of an ectopic pancreas in a peripancreatic lymph node. Therefore, a cystic lesion formed as a result of keratinization of the squamous epithelium with invasion into the pancreas could become a lymphoepithelial cyst of the pancreas.

Lymphoepithelial cyst of the pancreas

A case of lymphoepithelial cyst (LEC) of the pancreas is presented. A 48-year-old man complaining of general fatigue was found to have a heterogeneous water-dense mass protruding from the surface of the pancreas on plain computed tomography (CT). Dynamic CT disclosed septa within the mass. Magnetic resonance imaging, (MRI) showed a hypointense mass on T1-weighted imaging, and a hyperintense mass on T2-weighted imaging. MRI with gadolinium enhancement revealed septa within the mass. Endoscopic ultrasonography showed septa and fine echogenic structures within the cystic echoic lesion. Endoscopic retrograde pancreatography showed a normal duct system. Distal pancreatectomy with splenectomy was performed, with a suspected diagnosis of cystic neoplasms of the pancreas. Histopathologic examination disclosed LEC of the pancreas. Our case suggests that LEC should be considered in the differential diagnosis of cystic neoplasms of the pancreas.

CT of pancreatic neoplasms. Part II: The unusual tumors

The pancreas gives rise to a remarkable variety of neoplasms other than ductal adenocarcinoma. Although no individual type of tumor in this category is prevalent enough to qualify as common, most types are currently encountered with a frequency far greater than that in decades of the recent past. This change is largely the result of the expanded use of contemporary abdominal imaging. The unusual tumors of the pancreas vary greatly in their biologic behavior and, accordingly, in their clinical consequences and therapeutic requirements. Accurate diagnosis, therefore, can be of considerable clinical relevance. Not only is it worthwhile to distinguish one type of unusual pancreatic tumors from another, it is perhaps of even greater consequence to distinguish the unusual tumors from ordinary pancreatic adenocarcinomas. The goals of this discussion are to expand radiologic awareness of these uncommon but interesting pancreatic neoplasms and to increase familiarity with their diagnostically salient features.