Imaging of pancreatic cystic lesions with confocal laser endomicroscopy: an ex vivo pilot study

Background: The differential diagnosis of pancreatic cystic lesions (PCLs) is an increasingly common clinical challenge. Confocal laser endomicroscopy (CLE) may differentiate PCLs by imaging of the cyst wall. However, clinical experience is still limited, and better image definition and characterization of the cyst wall in a spectrum of cysts are needed. This experimental study aimed to expose detailed imaging characteristics of PCLs by CLE.

Methods: Patients who underwent surgery of a PCL were enrolled. During surgery, intravenous fluorescein (2.5 ml of 10%) was injected just prior to the ligation of blood vessels supplying the pancreas. The freshly excised specimens were transected along the long axis to fully expose the luminal surface. A Gastroflex-UHD CLE probe (pCLE) was used manually to acquire images directly from the surface of cyst wall. The specimen subsequently underwent cross-sectional histology. All recorded data were analyzed by two investigators for predefined and original image findings of PCLs.

Results: Ten cases were recruited into the study. All patients underwent surgery because of a mucinous cyst with worrisome features or a symptomatic PCL. Imaging was successful in all patients and differently shaped papillary projections (PP) were visualized in eight patients. Pathological examination of those patients confirmed 6 cases with Intraductal Papillary Mucinous Neoplasm (IPMN) and 2 cases with Mucinous Cystic Neoplasm (MCN). In two patients with serous cystadenoma, typical vascular network was visualized in one patient, and microcystic structures in the other. Three of the IPMNs were malignant. The loss of papillary margin integrity and significant fragmentation together with irregularity was detected in malignant IPMNs by CLE.

Conclusions: Pancreatic cyst epithelial wall can be visualized successfully by pCLE in ex vivo surgical specimens. Different papillary projections have been seen in all cases of IPMNs and MCNs. CLE has potential for identifying IPMN subtypes and for grading dysplasia.