The effect of EUS-guided pancreatic cyst ablation (PCA) on sonographic morphology and cyst fluid cytology is unknown. The aim of this study was to evaluate morphologic, cytologic, and change in cyst fluid DNA after PCA.

In a prospective single-center study, consecutive patients with suspected benign 10- to 50-mm pancreatic cysts underwent baseline EUS-FNA and EUS-PCA followed 2 to 3 months later by repeat EUS, cyst fluid analysis, and possible repeat PCA. Surveillance imaging after ablation was performed at least annually and classified as complete response (CR), partial response, or persistent, with <5%, 5% to 25%, and 25% of the original cyst volume, respectively.

Thirty-six patients underwent EUS-PCA with ethanol alone (n = 8) or ethanol and paclitaxel (n = 28), and CR occurred in 19 patients (56%). After EUS-PCA, EUS showed an increase in wall diameter in 68%, decreased number of septations in 24%, increased debris in 24%, loss of mural nodule or novel calcification in 21%, and alteration of fluid viscosity in 48%. Follow-up cytology showed increased epithelial cellularity in 27%, loss or decreased cellular atypia in 15%, increased or appearance of macrophages in 24%, and inflammatory cells in 15%. Postablation DNA amount increased and quality decreased in 71% each. Between the CR and non-CR patients, there was no significant difference in frequency of sonographic or cytologic features. In the CR group, mean DNA quantity was significantly increased after ablation (P = .023) without a change in quality (P = .136).

EUS-PCA induces morphologic and cytologic changes of pancreatic cysts, none of which appears to predict overall imaging-defined response to ablation. (Clinical trial registration numbers: NCT00233038 and NCT01643460.)