The role of ancillary tests in the evaluation and management of patients with negative and non-diagnostic pancreatic cyst aspirates

Endoscopic Ultrasound-Guided Fine Needle Aspiration Cytologic Evaluation of Intraductal Papillary Mucinous Neoplasm and Mucinous Cystic Neoplasms of Pancreas

OBJECTIVES

To evaluate the role of endoscopic ultrasound-guided fine needle aspiration cytology in identifying mucinous cystic lesions (MCLs) in histologically proven cases of intraductal papillary mucinous neoplasm (IPMN) or mucinous cystic neoplasm (MCN) and risk of malignancy associated with each cytologic category based on the Papanicolaou Society of Cytopathology (PSC) guidelines.

METHODS

All resected cases with histologic diagnosis of IPMN or MCN at our institution from January 1, 2004, to August 31, 2019, with associated cytology were included. Available cytology slides of nondiagnostic (ND), negative/benign (BN), and atypical cytology (AC) cases were reviewed and reclassified based on the PSC guidelines.

RESULTS

A total of 120 cases were identified, including 57 IPMNs with low-grade or moderate dysplasia (LGD/MD) and high-grade dysplasia (HGD), 34 MCNs with LGD/MD or HGD, and 29 IPMNs with invasive malignancy. After cytology slide review and reclassification, we observed that ND and BN cases were paucicellular and lacked ancillary testing (carcinoembryonic antigen levels or KRAS mutation analysis). The risk-of-malignancy rates were 33% for ND, 11% for BN, 28.5% for AC, 17% for MCL, and 100% for suspicious/positive cytologic diagnosis.

CONCLUSIONS

A multidisciplinary approach including combined use of cytology and ancillary testing is helpful in establishing a diagnosis of MCL and identifying associated malignancy.

Nondiagnostic fine-needle aspirates of the pancreas: A root cause analysis

BACKGROUND

Fine-needle aspiration (FNA) of the pancreas is considered the primary and least invasive diagnostic method in the evaluation of pancreatic lesions. A nondiagnostic sample may trigger repeat FNA or a more invasive diagnostic procedure. The goal of this study was to identify the root causes of nondiagnostic samples.

METHODS

We performed a retrospective review of FNAs of the pancreas categorized as nondiagnostic at our institution between 2008 and 2019. Medical records and slides were reviewed to identify the features described by imaging, rapid on-site evaluation, fluid chemistry, final cytology diagnosis, and final histology. A root cause analysis was performed using the Ishikawa (or fishbone) diagram and the 5 Whys method.

RESULTS

A total of 30 cases were identified: 11 adenocarcinomas, 6 cases of pancreatitis, 4 intraductal papillary mucinous neoplasms, 3 serous cystadenomas, 3 neuroendocrine tumors, 1 mucinous cystic neoplasm, 1 retention cyst, and 1 case of Brunner gland hyperplasia. The root causes identified were: man in 8 cases, machine in 1 case, method in 17 cases, and material in 18 cases. In many cases, more than 1 root cause contributed to the problem.

CONCLUSION

Material related errors contributed to the majority of nondiagnostic results and were primarily related to fibrotic cancers, chronic pancreatitis, absence of diagnostic criteria of cystic lesions, and technically challenging cases. Only 1 major interpretation error was identified. Sampling and interpretive errors contributed equally to man-related causes. For mucinous cysts, neoplastic mucin was difficult to identify in liquid-based preparations. Pathologists tended to issue a nondiagnostic categorization when epithelial cells are lacking and particularly when the nature and radiological impression of the cyst was not communicated.