Endosonography of complex cystic masses of the pancreas with clinicopathologic correlation

Endosonography (EUS) is a highly sensitive means for detecting cystic lesions of the pancreas. Cystic lesions may be classified as simple (single, round/oval, no associated solid component) or complex (multiple, irregular, septated, solid component). Of 231 patients who underwent EUS of the pancreas (Olympus GF-UM20), 25 were prospectively identified to have complex cystic lesions (11%) and these examinations and images were reviewed. A definitive histologic (18) or clinical diagnosis (2: insulinoma, MEN-1) was made in 20: 6 had adenoCA (mean=5.1 cm, range=3.1-5.6), 7 had cystadenomas (2.8cm, 1.8-4.2)(mucinous-3, serous-1, microcystic-1, unspec-2), 5 had neuroendocrine tumors (2.0 cm, 1.8-2.6)(islet cell-4, carcinoid-1). and 2 had complex pseudocysts. Of 5 unknown histology, 2 had a clinical diagnosis of pancreatitis, and on 1 year follow-up with repeat cross sectional imaging both were consistent with benign pseudocysts; one died from metastatic colon CA, 2 were lost to follow-up. Of the 6 adenoCA, 5 had a prominent, poorly demarcated/infiltrating solid component: 2 large cyst with associated mass, 2 primarily solid with cystic areas, 1 multiple cysts with discrete solid component; 1 had multiple cysts with no discrete mass. Six cystadenomas had multiple cysts arranged closely together, 3 had small solid components (mucinous, microcystic, unspec.), one (mucinous) had a prominent solid component, 2 had no discernible solid components (serous, mucinous); 1 had a single cyst (unspec.). All 4 islet cell tumors had well demarcated hypoechoic homogeneous solid masses with associated central (target lesion) or eccentric cysts. The carcinoid was a single 2.6 cm irregular cyst with a prominent solid component. Overall, 18 of 25 (72%) had a definite neoplasm. Conclusions: 1. Complex cystic masses are infrequently encountered, but up to 3/4's may be neoplastic. 2. EUS characterization may suggest the histological diagnosis: AdenoCA-larger, prominent solid component, not sharply demarcated from surrounding parenchyma; Cystadenoma-multiple closely arranged cysts, no or small solid component; Islet Cell-well demarcated, hypoechoic/homogeneous mass with central (target) or eccentric cyst.