Lymphoepithelial cyst of the pancreas

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.

Pearls and pitfalls of imaging features of pancreatic cystic lesions: a case-based approach with imaging-pathologic correlation

A variety of neoplastic and non-neoplastic lesions of the pancreas can present with a predominantly cystic architecture. These lesions are increasingly being detected as incidental findings on routine cross-sectional imaging following technological advances in these techniques and their widespread use. The different histopathological behaviors show various common and uncommon imaging findings, and some cases show similar appearance in spite of different histopathology. Each lesion requires specific management because of the differing risk of progression to malignancy, and an accurate imaging diagnosis is crucial. The typical imaging characteristics that differentiate pancreatic cystic lesions have been well described and fully summarized. However, in addition to a small percentage of cases that shows uncommon imaging findings, a substantial percentage of cystic lesions shows overlapping imaging findings that can lead to radiological misdiagnosis. For appropriate diagnosis and optimal treatment strategy, it is important to know the uncommon and overlapping imaging findings of these lesions, in addition to familiarity with the typical aspects. In this article, we reconfirm the well-known characteristic imaging features of pancreatic cystic lesions and present several diagnostically challenging cases, focusing on the uncommon and overlapping imaging findings.

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.

Lymphoepithelial cyst of the pancreas

Cystic lesions of the pancreas can be divided into true cysts, pseudocysts, and cystic neoplasms. Lymphoepithelial cysts (LECs) are a type of true cyst that can mimic pseudocysts and cystic neoplasms. LECs are rare lesions; fewer than 90 cases have been reported in the English language literature. The case of a 60-year-old man with an LEC of the pancreas is reported. He was admitted with upper abdominal discomfort. Computed tomography showed a 64 × 39 mm cystic mass in the retroperitoneum behind the duodenum and inferior caval vein. Magnetic resonance imaging revealed a right-sided mass on T1-weighted imaging, with a clear boundary between the mass and its surroundings, except for the pancreas. The mass had an inhomogeneous intensity on T2-weighted imaging. Within the mass, small floating nodules with low intensity were seen. Endoscopic ultrasound showed many high-echoic nodules and smaller grains scattered everywhere in the mass. Fine needle aspiration and cytologic examination were performed. Characteristic chylaceous fluid was obtained in which anucleate squamous cells were found. There were also a few atypical large cells with irregularly shaped marked nucleoli and degenerative cytoplasm. Cytologic diagnosis was suspicious for malignancy. The lesion was diagnosed as a retroperitoneal cyst, probably of pancreatic origin. Since a neoplastic lesion could not be ruled out, surgery was performed. The lesion was palpable on the dorsal side of the second portion of the duodenum. The mass was completely resected. Macroscopically, the lesion was a multilocular cyst with a thin septal wall. The cyst was filled with cottage cheese-like substance. Microscopically, the cyst wall was composed of stratified squamous epithelium and dense subepithelial lymphatic tissue with developed lymph follicles. The epithelial cells had no atypia. The histopathologic diagnosis was LEC of the pancreas. The patient's postoperative course was good.

Acinar cell cystadenoma (acinar cystic transformation) of the pancreas: the radiologic-pathologic features

Acinar cystic transformation of the pancreas is also known as acinar cell cystadenoma (ACC), and this is an extremely rare benign lesion that was first described in April 2002. We report here on a case of a previously asymptomatic patient with pancreatic ACC and this was diagnosed by computed tomography (CT) and magnetic resonance imaging (MRI). To the best of our knowledge, there is no previous report concerning the CT or MRI features of ACC in the medical literature. We present here the CT, MRI and pathological findings of pancreatic ACC.

MR imaging of cystic lesions of the pancreas

Pancreatic cystic lesions are relatively common imaging findings and may be secondary to both benign and malignant disease processes. Accurate characterization of the internal features of a cyst--including fluid, hemorrhage, septa, and enhancing soft-tissue components--is important to guide the differential diagnosis, and cross-sectional magnetic resonance (MR) imaging is the optimal modality for depicting these features. Cystic lesions of the pancreas may be divided into two categories: (a) primary cystic lesions, which include pseudocysts, serous cystadenomas, various mucin-containing cysts (mucinous nonneoplastic cysts, mucinous cystadenomas, mucinous cystadenocarcinomas, intraductal papillary mucinous neoplasms), and lymphoepithelial cysts, and (b) various solid neoplasms undergoing cystic changes (ductal adenocarcinoma with cystic features, pseudopapillary tumors of the pancreas, and cystic neuroendocrine tumors). Primary cystic lesions are more common than solid neoplasms with cystic changes. Knowledge of the varied MR imaging appearances of pancreatic cystic lesions may help radiologists achieve greater specificity in diagnostic reporting.

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

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.

[Cystic lesions of the pancreas]

Most cystic lesions of the pancreas are pseudocysts caused by acute or chronic pancreatitis. Congenital cysts are rare and may occur in congenital syndromes like von Hippel-Lindau syndrome. Cystic tumors of the pancreas may be difficult to distinguish clinically; however, because of their malignant potential, in particular in cases of mucinous types, diagnostic verification is crucial. Hence, in all cases of cystic lesions of the pancreas, which are not a sequela of an etiological confirmed acute or chronic pancreatitis, a cystic neoplasm must be ruled out. Differential diagnosis may be difficult even with ultrasonography, computertomography, endoscopic retrograde cholangiopancreatography and serum analyses; endoscopic ultrasound, magnetic resonance tomography and analysis of the cyst content may be of particular value. The therapeutic approach for pseudocysts is now well established and guided by symptoms and complications. If a cystic neoplasm is suspected, surgical resection of the complete lesion is warranted.

CONCLUSION

The most important differential diagnosis in all cystic lesions of the pancreas with atypical presentation includes a cystic neoplasm. Therefore complete resection is indicated whenever the suspicion cannot be ruled out.