Benign Pancreatic Cystic Neoplasms: Does F/U EUS-FNA Confirm or Alter the Diagnosis

Abstract

Pancreatic cystic neoplasm often provides a diagnostic challenge. Conventional imaging (CT, US) is less than optimal in its ability to differentiate benign (serous cystadenoma), potentially malignant (mucinous cystadenoma), or malignant cysts (mucinous cystadenocarcinoma). Recently, EUS has demonstrated to be an improved imaging modality in the differential diagnosis of pancreatic (cyst fluid analysis) cystic neoplasm including parenchymal features and cyst fluid analysis. CEA, viscosity, CA 19-9, amylase levels collectively can differentiate pancreatic cystic lesions (previously reported by our group). Follow-up of presumed serous cystadenoma has not been reported. AIM: To determine if F/U pancreatic cyst fluid analysis of serous and mucinous cystadenoma confirm previously established diagnosis. METHODS: Over a 5-year period, 121 pts presented for evaluation of pancreatic cystic neoplasm. Of these, 14 pts underwent F/U EUS cyst fluid analysis at 12-18 month intervals. Based on previously established criteria, differentiating serous and mucinous cystic neoplasm: serous cystic neoplasm (CEA <480, VIS <1.6, CA19-9 <700) and mucinous cystic neoplasm (CEA >480, VIS ≥1.6, CA19-9 >9000), 11 had serous cystadenomas, while 3 had mucinous cystadenomas. Pts with mucinous cystadenomas refusing surgery because of age, co-morbid illness, or pt choice. Cyst fluid analysis included CEA, CA 19-9, viscosity, amylase/lipase, and cytology. A minimum of 2 cc of fluid was necessary to obtain complete set of cyst fluid markers. Size of lesions was 2.2-5.5 cm (mean 3.4 cm). RESULTS: Repeat cyst fluid analysis was available in all 14 pts. Comparative data is listed in the table below. No appreciable differences were seen in pts with serous cystic lesions cyst fluid analysis with respect to CEA, CA19-9, viscosity, and amylase levels. Pts with markers suggesting MCA had progression of cyst fluid levels including CEA (30% increase) and CA 19-9 (25% increase). CONCLUSIONS: Cyst fluid marker values differentiating serous from mucinous cystic lesions has been previously established. F/U markers at 12-18 months confirm the nature of the cystic lesion and can be used to follow such lesions in those treated conservatively. Serous cystic lesions show stability of cyst fluid markers, whereas mucinous cystic lesions demonstrate progression and/or instability.