Lymphoepithelial cysts of the pancreas:a management dilemma

Pancreatic lymphoepithelial cysts（LECs） are rare,benign lesions that are typically unexpected post-operative pathological findings. We aimed to review clinical, radiological and pathological features of LECs that may allow their preoperative diagnosis. Histopathology databases of two large pancreatic units were searched to identify LECs and notes reviewed to determine patient demographic details, mode of presentation, investigations, treatment and outcome. Five male and one female patients were identified. Their median age was 60 years. Lesions were identified on computed tomography performed for abdominal pain in two patients, and were incidentally observed in four patients. Five LECs were located in the tail and one in the body of the pancreas, with a median cyst size of 5 cm. Obtaining cyst fluid was difficult and a largely acellular aspirate was yielded. The pre-operative diagnosis was mucinous cystic neoplasm in all patients. This series of patients were treated distal pancreatectomy and splenectomy. A retrospective review of radiological examinations suggested that LECs have a relatively low signal on T2 imaging and a high signal intensity on T1 weighted images. LECs appear more common in elderly males, and are typically incidental, large, unilocular cysts. Close attention to signal intensity on MRI may allow preoperative diagnosis of these lesions.

Methylation changes at the GNAS imprinted locus in pancreatic cystic neoplasms are important for the diagnosis of malignant cysts

BACKGROUND Guanine nucleotide-binding protein,alpha stimulating(GNAS)mutations are characteristic of intraductal papillary mucinous neoplasms(IPMNs).Pancreatic ductal adenocarcinomas(PDACs)harboring GNAS mutations originate in IPMNs.GNAS is a complex imprinted locus that produces five transcripts regulated by differential methylated regions,NESP55,GNASAS,GNASXL,GNAS1A,and GNAS.AIM To evaluate if methylation changes in the differential methylated regions of GNAS locus contributed to malignant progression of pancreatic cysts.METHODS GNAS locus methylation was analyzed in archival pancreatic cyst fluid(PCF)obtained by endoscopic ultrasound with fine-needle aspiration by methylation specific–multiplex ligation dependent probe amplification.Results were normalized and analyzed using Coffalyser.Net software.RESULTS Fifty-two PCF samples obtained by endoscopic ultrasound with fine-needle aspiration and previously characterized for KRAS and GNAS mutations were studied.The final diagnoses were surgical(11)and clinicopathological(41),including 30 benign cysts,14 pre-malignant cyst,and eight malignant cysts.Methylation changes at NESP55,GNASAS,GNAS1A,and especially GNASXL were more frequent in malignant cysts,and NESP55 and GNASAS were useful for diagnosis.A combined variable defined as“GNAS locus methylation changes”was significantly associated with malignancy(6/8 malignant cysts and only 2/20 benign cysts)and improved classification.Hypermethylation in both maternally(NESP55)and paternally(GNASXL)derived promoters was found in 3/3 PDACs.CONCLUSION This is the first study to identify methylation changes in the GNAS locus,improving the diagnosis of malignant pancreatic cysts and suggesting a role in progression to PDAC.

胰腺囊性疾病的CT诊断

目的 介绍不同疾病导致的胰腺囊性疾病的CT表现及相关临床手术病理回顾 ,提高对本组疾病的认识。方法 胰腺常规CT扫描 ,10mm层厚及层间距 ,对较小病灶 2～ 5mm薄层扫描 ,平扫加强化。结果 4例胰腺假性囊肿 ,2例胰腺多发性脓肿 ,1例囊腺瘤 ,1例坏死性胰腺癌 ,1例胰腺寄生虫性囊肿。结论 胰腺囊性疾病是一组含囊病变的总称。以发病率统计最常见是胰腺假性囊肿 ,其次为囊性肿瘤 ,胰腺脓肿、寄生虫性囊肿少见。