Fluid analysis prior to surgical resection of suspected mucinous pancreatic cysts. A single centre experience

Objective: EUS-FNA cytology and fluid analysis are frequently utilized to evaluate pancreatic cysts. Elevated cyst fluid CEA is usually indicative of a mucinous pancreatic cyst but whether CEA or amylase values can subclassify various mucinous cysts is unknown. The purpose of this study is to determine whether cyst fluid CEA and amylase obtained by EUS-FNA can differentiate between mucinous cystic neoplasms (MCNs) and intraductal papillary mucinous neoplasms (IPMNs).

Methods: Using our prospective hospital EUS and surgical databases, we identified all patients who underwent EUS of a pancreatic cyst prior to surgical resection, in the last 10 years. Cysts were pathologically sub-classified as MCNs or IPMNs; all other cysts were considered non-mucinous. Values of cyst fluid CEA and amylase were correlated to corresponding surgical histopathology and compared between the two groups.

Results: 134 patients underwent surgery for pancreatic cysts including 82 (63%) that also had preoperative EUS. EUS-FNA was performed in 61/82 (74%) and cyst fluid analysis in 35/61 (57%) including CEA and amylase in 35 and 33 patients, respectively. Histopathology in these 35 cysts demonstrated nonmucinous cysts in 10 and mucinous cysts in 25 including: MCNs (n=9) and IPMNs (n=16). Cyst fluid CEA (p=0.19) and amylase (p=0.64) between all IPMNs and MCNs were similar. Between branched duct IPMNs and MCNs alone, cyst fluid CEA (p=0.34) and amylase (p=0.92) were also similar.

Conclusion: In this single center study, pancreatic cyst fluid amylase and CEA levels appeared to be of limited value to influence the differential of mucinous pancreatic cysts. Larger studies are recommended to evaluate this role further.