Probe based confocal laser endomicroscopy of the pancreatobiliary system

Table 1 Interpretation of findings on confocal endomicrosopy and findings on confocal laser endomicroscopy for specific pancreatic lesions

Findings on CLE	Interpretation
Normal
Reticular pattern seen in normal tissue and smaller than blood vessels[6]	Lymphatics
Thick white bands[52]	Angiogenesis
Reticular arrangement of dark-gray bands on a light-gray background and normal vessels (thin and regular) and no visible glands[9]	Normal common bile duct chorion
Black clumps[69]	Areas of decreased fluorescein uptake
Large white streaks/bands[69]	Dilated, tortuous blood vessels
Loss of mucosal architecture[6,69]	Fibrosis
Multiple thin white bands[15]	Vascular congestion
Thin dark bands forming a reticular pattern (diameter < 20 μm)	Submucosal collagen network
Thin white bands (diameter < 20 μm)	Small caliber blood vessels
Light grey background	Lymphatic sinuses
Abnormal
Thick collagen bundles	Desmoplasia (growth of fibrous and connective tissue)
Thick white bands (diameter > 20 μm)	Malignant bile duct stricture
Multiple white bands	Inflammatory bile duct stricture
Dark clumps and epithelium	Malignancy
Type of pancreatic lesion	Characteristics on nCLE
Exocrine adenocarcinomas	Dark cells aggregates with pseudo-glandular aspects
	Straight hyperdense elements more or less thick corresponding to tumoral fibrosis
Tumors with acini cells and neuroendocrine tumors	Very dense network of small vessels on a dark background
Serous cystadenoma	Highly dense and dynamic network of blood capillaries, present in the superficial layer of the cyst wall, superficial vascular network, (pathognomonic)
Intraductal papillary mucinous neoplasm	Papillae characterized by two epithelial borders surrounding a bright vascular flow
Mucinous cystadenoma neoplasm	An epithelial border lined the cyst wall, with or without deep blood vessels, and without papillary organization

CLE: Confocal laser endomicroscopy; nCLE: Needle CLE.

Table 2 Performance of characteristics of findings on confocal laser endomicroscopy for pancreatobiliary strictures

Criterion	Author and the description of the examined area	Sensitivity	Specificity	PPV	NPV
	Meining et al[41,53]
Malignant biliary strictures	Loss of reticular pattern of epithelial bands of less than 20 μm	83%	88%	NR	NR
	Irregular epithelial lining, villi, or gland-like structures
	Tortuous, dilated, and saccular vessels with inconsistent branching
	Presence of “black areas” of more than 60 to 80 μm (focally decreased uptake of fluorescein)
	Meining et al[20]
Suggestive ofmalignancy	Thick, dark bands (> 40 μm)	98%	67%	71%	97%
	Thick, white bands (> 20 μm)
	Dark clumps
	Epithelium visualized (villi, glands)
	Fluorescein leakage
Suggestive ofbenign strictures	Thin, dark (branching) bands
	Thin, white bands
	Meining et al[14]
Normal bile ducts	Reticular network of thin dark branching bands (< 20 μm)	97%	33%	80%	80%
	Light gray background
	Vessels < 20 μm
Malignant biliary strictures	Thick white bands (> 20 μm)
	Thick dark bands (> 40 μm),
	Dark clumps
	Epithelial structures
	Normal vessels (thin and regular)
	No visible glands
	Giovannini et al[18]
Benign IPMN	Finger-like projections corresponding to villous changes of intestinal IPMN type	NR	NR	NR	NR
Pancreatic adenocarcinoma	Vascular leakage with irregular vessels with leakage of fluorescein into the tumor
	Large dark clumps which correspond to humps of malignant cells
Benign Lymph nodes	Diffuse small cells into a homogeneous stroma with normal vascularization
Malignant lymph nodes	Glandular structures with dark cells, large dark clumps and neo-vascularization with huge leakage of fluorescein
	Filoche et al[56]
Benign inflammatory strictures of the common bile duct	Vascular congestion but still regular	NR	NR	NR	NR
	Roughness aspect
	Increased inter-glandular space
	Thickened reticular structure
	Caillol et al[15]
Inflammatory stenosis	Multiple thin white bands (Vascular congestion)	96.3%	63.6%	68.4%	95.5%
	Roughness aspect
	Increased inter-glandular space
	Thickened reticular structure

IPMNs: Intraductal papillary mucinous neoplasms; NR: Not reported; PPV: Positive predictive value; NPV: Negative predictive value.