Confocal laser endomicroscopy in the “in vivo” histological diagnosis of the gastrointestinal tract

Table 1 Confocal criteria for squamous cell epithelium and carcinoma

	Squamous cell epithelium	Squamous cell neoplasia
Cellular criteria	Dark, homogeneous epithelial cells; regular architecture and clearly visible borders	Dark cells with different sizes; no clearly visible borders; irregular architecture
Vascular criteria	Capillaries directed to luminal epithelium without leakage of fluorescein	Twisted and irregular vessels; elongated capillaries; capillary leakage

Table 2 Confocal laser endomicroscopy (CLE) classification of Barrett’s esophagus

Confocal diagnosis	Vessel architecture	Crypt architecture
Gastric-type epithelium	Capillaries with a regular shape only visible in the deeper parts of the mucosal layer	Regular columnar-lined epithelium with round glandular openings and typical cobblestone appearance
Barrett’s epithelium	Subepithelial capillaries with a regular shape underneath columnar-lined epithelium visible in the upper and deeper parts of the mucosal layer	Columnar-lined epithelium with intermittent dark mucin in goblet cells in the upper parts of the mucosal layer. In the deeper parts, villous, dark, regular cylindrical Barrett’s epithelial cells are present
Neoplasia	Irregular capillaries visible in the upper and deeper parts of the mucosal layer. Leakage of vessels leads to a heterogeneous and brighter signal intensity within the lamina propria	Black cells with irregular apical and distal borders and shapes, with strong dark contrast against the surrounding tissue

Table 3 CLE classification of patterns in colorectal lesions

Grading	Vessel architecture	Crypt architecture
Normal	Hexagonal, honeycomb appearance that presents a network of capillaries outlining the stroma surrounding the luminal openings of the crypts	Regular luminal openings and distribution of crypts covered by a homogeneous layer of epithelial cells, including goblet cells
Regeneration	Hexagonal, honeycomb appearance with no increase or only a slight increase in the number of capillaries	Star-shaped luminal crypt openings or focal aggregation of regular-shaped crypts with a regular or reduced amount of goblet cells
Neoplasia	Dilated and distorted vessels with increased leakage; irregular architecture, with little or no orientation to the adjoining tissue	Ridge-lined irregular epithelial layer with loss of crypts and goblet cells; irregular cell architecture, with little or no mucin