[396] Endoscopic Ultrasound-Guided Fine-Needle Aspiration (EUS FNA) of Cystic Pancreatic Lesions: What Is the Value of Molecular and Chemical Analysis of Cyst Fluid in Diagnostic and Nondiagnostic Samples?

Wenping Li, Susie Nguyen, Nadim Haddad, Therese Cermak, Mary Sidawy. MedStar Georgetown University Hospital, Washington, DC

Background: Cystic lesions of the pancreas are often complex and heterogeneous with low diagnostic yield by EUS FNA. We evaluated whether molecular analysis for loss of heterozygosity (LOH) and KRAS point mutations, as well as chemical analysis for CEA, assisted in classifying these lesions.
Design: We identified 65 cystic pancreatic lesions collected by EUS FNA since 2010 that had cyst fluid sent for molecular testing and chemical analysis. The cytologic, histologic, molecular and chemical results were reviewed.
Results: Of 65 cases, EUS FNA results were nondiagnostic in 74% (48) compared with our overall nondiagnostic rate for pancreatic EUS FNA of 26%. The 48 nondiagnostic samples had material sent for molecular analysis. KRAS mutations were detected in 15 (31%) and 7 had surgical follow-up with results summarized in Table 1.

Table 1. Nondiagnostic EUS FNAs
Surgical follow-upKRASLOHCEA (ng/ml)*
*L=low (<192) H=high (>192)

KRAS mutations were detected for intraductal papillary mucinous neoplasm with low grade dysplasia (IPMN, LG) and invasive adenocarcinoma (AdenoCA) but not in mucinous cystic neoplasms (MCN) or mucinous metaplasia (MM). Fluid analysis for CEA showed elevation in most mucinous lesions (except 1 IPMN, LG and 1 AdenoCA). Of 17 diagnostic EUS FNAs, 6 had surgical follow-up and are summarized in Table 2.

Table 2. Diagnostic EUS FNAs
FNA DiagnosisSurgical follow-upKRASLOHCEA (ng/ml)*
Mucinous cystic lesionIPMN, LGYNL
Mucinous cystic lesionIPMN, inv CA--H

KRAS mutation was detected in IPMN, LG while the IPMN with invasive carcinoma (IPMN, inv CA) was not tested for KRAS but had elevated CEA. LOH was detected in a gastrointestinal stromal tumor (GIST) and a pancreatic endocrine tumor (PEN).
Conclusions: Our results show that a combination of KRAS mutations and/or high CEA levels identified all 8 mucinous neoplasms and AdenoCA (6 of which were nondiagnostic by EUS FNA). The remaining tumors (SPN, ITPN, GIST and PEN) had low CEA levels and no KRAS mutations. LOH was detected only in GIST and PEN. We conclude that when cytologic material is diagnostic, molecular and chemical analysis may not provide additional information. However, in nondiagnostic cases, cyst fluid analysis may be useful in identifying lesions that need close clinical follow-up.
Category: Cytopathology

Tuesday, March 5, 2013 2:15 PM

Proffered Papers: Section C, Tuesday Afternoon


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