Original Articles
Macrocystic pancreatic cystadenoma: the role of EUS and cyst fluid analysis in distinguishing mucinous and serous lesions

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Abstract

Background

Benign pancreatic serous cystadenoma usually is morphologically distinguishable from mucinous cystadenomas, which require resection because of their malignant potential. A macrocystic variant of serous cystadenoma recently has been described, rendering this important distinction more difficult. The aim of this study was to determine the EUS and tumor marker characteristics of mucinous cystadenoma compared with macrocystic serous cystadenomas.

Methods

Medical records for consecutive patients seen between 1995 and 2002, with a histopathologic diagnosis of mucinous cystadenoma or macrocystic serous cystadenoma after surgery, who had undergone a detailed EUS examination, including EUS-guided FNA, were retrospectively reviewed.

Results

A resection specimen was available for 32 mucinous cystadenomas and 9 macrocystic serous cystadenomas. No significant differences were observed with regard to clinical data (age, gender, presence of symptoms), lesion size, and location within the pancreas. All mucinous cystadenomas had a discernible cyst wall (thickened, 66%; focal parietal nodules, 25%) compared with 56% of macrocystic serous cystadenomas (p<0.0001). A thick echo content also was more frequent in mucinous cystadenoma (56% vs. 11%; p = 0.04; statistical significance removed by the Bonferroni correction). Microcysts were only observed in macrocystic serous cystadenomas (44%; p = 0.0008). The combination of a cyst wall that is thickened and the absence of microcysts had a sensitivity of 100% and specificity of 78% for the diagnosis of mucinous cystadenoma compared with macrocystic serous cystadenoma. Although intracystic carbohydrate-associated antigen 72-4 and mucins M1 were non-discriminatory, low carcinoembryonic antigen (<5 ng/mL) and carbohydrate-associated antigen 19-9 (<50,000 U/mL) values were found in macrocystic serous lesions (respectively, 100% and 100%; p = 0.0002 and p = 0.0002).

Conclusions

Although there is considerable overlap, helpful EUS characteristics that differentiate mucinous cystadenoma from macrocystic serous cystadenoma include a thick cyst wall and microcysts. These features, coupled with analysis of aspirated fluid for tumor markers (especially carcinoembryonic antigen), should help to confirm the diagnosis.

Section snippets

Patients

The clinical and EUS characteristics, as well as analysis of cyst fluid obtained by EUS-guided FNA (EUS-FNA), were retrospectively studied in 41 consecutive patients who presented between 1995 and 2002 with mucinous or macrocystic serous cystadenoma of the pancreas. All patients underwent endoscopic examinations and surgical procedures after written informed consent was obtained.

Inclusion criteria

The surgical pathology diagnosis (from histopathology files) was available for 32 patients with mucinous cystadenoma

Results

Data were available for 41 EUS examinations (41 patients). Patient characteristics and mode of presentation for mucinous cystadenoma (n = 32) and macrocystic serous cystadenoma (n = 9) were similar in both groups (Table 1).

Discussion

With better knowledge of the morphologic aspects of pancreatic cystadenomas, management strategies can be expected to improve. Unfortunately, EUS data for these lesions are limited. Until recently, pancreatic cystic tumors presenting as predominately unilocular macrocysts were resected surgically. The recent description of a macrocystic form of serous cystadenoma3., 4., 5., 6., 7., 8., 9., 10., 11., 12., 13., 14., 15., 16., 17. necessitates re-evaluation of morphologic data and expanded

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