A243 A RETROSPECTIVE REVIEW OF THE RADIOGRAPHIC DIAGNOSIS AND SURGICAL RESECTION RATES OF PANCREATIC SEROUS CYSTS

Background

Pancreatic cystic lesions are increasingly identified in persons undergoing abdominal imaging. Serous cystic neoplasms (SCNs) have a very low risk of malignant transformation. Resection of SCNs is not recommended in the absence of related symptoms. The accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) to identify SCNs is not known and may impact clinical care.

Aims

To evaluate the accuracy of computed tomography (CT) and magnetic resonance imaging (MRI) for the diagnosis of SCN. To see how this can impact the decision to resect suspected SCNs.

Methods

Retrospective cohort study of patients from the University Health Network with suspected SCNs from 2017–2020 who underwent either a CT or MRI of the abdomen. Reports noting pancreatic cystic lesions were identified and reviewed. Only cases with suspected SCNs were included. Clinical (age, sex, symptoms, treatment) and radiographic (type of imaging, reported cyst characteristics) data was collected. Pathology was reviewed for all cases where the cysts was biopsied or resected during follow-up. The gold standard for the diagnosis for SCN was pathology of resected specimen or EUS-guided biopsy cytopathology showing no evidence of a mucinous lesion, CEA level below 10ug per L and amylase level below 50 U/L.

Results

163 patients were included in the study. 99 (61%) were female and 98 (60%) underwent CT scan. EUS-guided biopsy was performed in 24 (15%) of patients and 8 (5%) had surgical resection. Multidisciplinary review was performed in 6 of the 8 cases that went to surgery. Of the resected specimens, 5 (63%) were SCN, 1 was a mucinous cystic lesion, 1 was a neuroendocrine tumor and 1 was a carcinoma. Two patients underwent EUS evaluation prior to surgical resection. In one case SCN was resected when EUS reported an undetermined cyst type. Reasons for surgical resection were: the diagnosis of serous cyst was not definitive (n=5), symptoms (n=2), and high-risk mucinous cystic neoplasm identified on EUS (n=1). Of 30 patients with pathology available, 15 (50%) were confirmed to have a SCN. CT and MRI had a sensitivity, specificity, positive predictive value and negative predictive value of 93%, 25%, 52% and 80%, respectively.

Conclusions

Surgical resection for SCN lesions is driven by diagnostic uncertainty after cross-sectional imaging. Multidisciplinary review and EUS evaluation may improve diagnostic accuracy and should be considered prior to surgical resection of possible SCN lesions.

Funding Agencies

None

A277 DISCREPANCIES IN EUS-FNA CYTOPATHOLOGY AND SURGICAL SPECIMEN PATHOLOGY FOR HIGH RISK PANCREATIC MUCINOUS CYSTIC LESIONS: A CASE SERIES

Background

Endoscopic ultrasound guided fine needle aspiration (EUS-FNA) is the primary method of sampling pancreatic cystic lesions with reported specificity near 100% for diagnosing malignancy. Discrepant positive malignant cytopathology with final surgical pathology of pancreatic cystic lesions has not previously been described.

Aims

To present a case series and review the literature regarding the implications of positive malignant cytology with discrepant surgical pathology for high risk pancreatic mucinous cystic lesions.

Methods

Patient demographics, clinical history, procedure details, pathology evaluations and follow-up were collected. A thorough literature review was performed.

Results

Three patients with high-risk pancreatic cystic lesions on cross-sectional imaging underwent EUS-FNA evaluation. None of these patients had a history of pancreatitis. Cytology was reported as positive for adenocarcinoma in all patients by separate gastrointestinal cytopathologists. All patients underwent surgical resection. The pathology for all resected specimens were reported as intraductal papillary mucinous neoplasm. The resected cysts for two patients demonstrated foci of high-grade dysplasia and the third noted low grade dysplasia. All surgical pathology underwent consensus review by three separate gastrointestinal pathologists. None of the patients were treated with adjuvant chemotherapy. All patients have been followed post-operatively with surveillance magnetic resonance imaging with no evidence of recurrence to date (median follow-up time 239 days, range 133 – 447 days).

Conclusions

This phenomenon sheds light on the potential for variable interpretations of EUS-FNA cytopathology and surgical resection pathology for high risk pancreatic cystic neoplasms. EUS-FNA may identify foci of adenocarcinoma that is not seen on surgical pathology specimens. Further research is required to examine the long-term outcomes of these patients.

Funding Agencies

None