Novel technique for diagnosis of mucinous cystic neoplasms: in vivo and ex vivo confocal laser endomicroscopy

A 51-year-old woman presented with abdominal pain, and a CT scan of the abdomen revealed a cystic lesion in the tail of the pancreas measuring 4.4 cm × 3.8 cm. An EUS demonstrated a 4.1 cm × 4.0 cm anechoic cystic lesion without main pancreatic duct involvement. The differential diagnosis was broad and included intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm (MCN), and serous cystadenoma (SCA). However, MCN was slightly higher on the differential diagnosis because these lesions are typically seen in middle-aged women, with the majority of lesions seen in the pancreatic body or tail without communication with the main pancreatic duct.

Here we present a relatively new technique, needle-based confocal laser endomicroscopy (nCLE), which allows for real-time image acquisition during EUS. The nCLE demonstrated solitary epithelial bands without any papillary conformation (Video 1, available online at www.VideoGIE.org) (Fig. 1). These bands are best described as having a horizon-type configuration with variable thickness, suggestive of a diagnosis of MCN.¹ FNA revealed a carcinoembryonic antigen (CEA) level of 75.5 ng/mL, and cytologic analysis demonstrated the presence of mucin.

Figure 1.

In vivo EUS needle-based confocal laser endomicroscopic view showing solitary epithelial bands without papillary conformation.

Although MCNs can progress to malignancy, the decision regarding surgical resection is often institution dependent.² Considering the size of the cystic lesion and the strong suspicion of a mucinous cyst (either IPMN or MCN), a decision was made for distal pancreatectomy. After surgical resection, ex vivo probe-based confocal laser endomicroscopy (pCLE) examination of the cyst was performed with a Gastroflex ultrahigh-definition probe (Mauna Kea Technologies, Paris, France). The ex vivo pCLE findings correlated with the in vivo EUS-nCLE findings (Video 1; Fig. 2), and surgical histopathologic analysis revealed an MCN with low-grade dysplasia (Fig. 3).

Figure 2.

Postsurgical ex vivo confocal laser endomicroscopic view of features consistent with in vivo findings showing solitary epithelial bands.

Figure 3.

Histopathologic view of surgical specimen showing focal atypical glands (arrows) with adjacent area demonstrating fibrosis and confirming a low-grade mucinous neoplasm (H&E, orig. mag. ×20).

Here we present in vivo EUS-nCLE findings suggestive of MCN that were correlated with the results of postsurgical ex vivo pCLE examination. Three major trials have been conducted to assess the accuracy of nCLE findings in diagnosing pancreatic cystic lesions (PCLs).3, 4 For MCNs specifically, 1 study found a diagnostic accuracy of 90% for nCLE, with a sensitivity of 67% and specificity of 96%.¹ However, given the novelty of the technique, these studies are limited by their sample size and surgical histopathologic confirmation. This case illustrates how nCLE can further supplement EUS and cytologic analysis in the workup of MCNs. Our study adds to the increasing body of literature demonstrating the utility of nCLE in the diagnosis and management of PCLs.

Disclosure

All authors disclosed no financial relationships relevant to this publication.

Supplementary data

Video 1

EUS in-vivo needle-based confocal laser endomicroscopy (CLE) and postsurgical ex-vivo CLE compared with final histopathologic analysis confirming a mucinous cystic neoplasm.