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

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.

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.

Cystic tumors of the pancreas: imaging and management

Cystic tumors of the pancreas are a subset of rare pancreatic tumors that vary from benign to malignant. Many have specific imaging findings that allow them to be differentiated from each other. This article (1) reviews the imaging features of the common cystic pancreatic lesions, including serous microcystic adenoma, mucinous cystic tumor, intraductal papillary mucinous tumor, and solid pseudopapillary tumor, and including the less common lesions such as cystic endocrine tumors, cystic metastases, cystic teratomas, and lymphangiomas; and (2) provides comprehensive algorithms on how to manage the individual lesions, with recommendations on when to reimage patients.

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.

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

Review of endoscopic ultrasound-guided fine-needle aspiration cytology

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

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.

Image-diagnostic features of mature cystic teratomas of the pancreas: report on two cases difficult to diagnose preoperatively

This report documents the findings of two rare cases of mature cystic teratoma of the pancreas. Although they could not be diagnosed preoperatively, our retrospective report suggests that the combined diagnosis of ultrasonography (US), enhanced computed tomography (CT), and magnetic resonance cholangiopancreatography (MRCP) might allow differentiation from other cystic lesions such as mucinous cystic tumors (MCTs) and intraductal papillary-mucinous tumors (IPMTs). Since the cystic teratomas were both filled with keratinous and sebaceous material, they were echogenic, appearing as solid masses on US. Enhanced CT showed their cystic nature, with values slightly higher than water, and MRCP revealed defects of internal signals.

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.

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.

Macrocystic serous adenoma of the pancreas

Macrocystic serous adenoma of the pancreas (MSAP) is a rare neoplasm. Its preoperative diagnosis by physical examination and imaging studies is challenging, if not impossible. In recent years, a few cases of MSAP with correct cytodiagnosis by transabdominal fine-needle aspiration (TFNA) have been documented. This paper reports two cases of MSAP that were successfully diagnosed by TFNA cytology. Two adult women presented with epigastric discomfort. Abdominal imaging studies revealed a large pancreatic cystic lesion in both cases. TFNAs of the pancreatic lesions were subsequently performed and revealed a clear serous fluid containing small monolayered sheets of benign cuboidal epithelial cells with scant, clear or granular cytoplasm, vesicular nuclei and micronucleoli. The cell cytoplasm stained positively with periodic acid-Schiff (PAS) and negatively with PAS with prior digestion with diastase (PASD). The cytological findings in both cases were similar and suggested a serous cystadenoma. The two pancreatic lesions were removed by Whipple's operation. They showed features of a macrocystic serous adenoma of the pancreas that were characterized by a small number of large cystic cavities lined by a single layer of non-mucus secreting, PAS-positive and PASD-negative cuboidal epithelial cells. By electron microscopy, the epithelial lining cells showed short and aborted apical microvilli, well-formed desmosomes and a large amount of intracytoplasmic glycogen, suggesting a centroacinar ductal cell origin.

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.