Table 1. Definitions of Histologic Features Evaluated in the Mucosal Biopsies.

Features	Definition	Cutoff value
Squamous
Basal hyperplasia	Thickening of basal layers of squamous epithelium	Presence or absence
Elongation of papillae	Height of papillae > 50% of epithelium thickness	Presence or absence
Spongiosis	Widening of intercellular spaces due to edema	Presence or absence
Ballooning degeneration	Enlarged squamous cells with intracellular edema	Presence or absence
Parakeratosis	Superficial layers of nucleated squamous cells with dense keratin	Presence or absence
Dysplasia	Neoplastic squamous epithelium confined above the basement membrane	Presence of absence
Inflammation within the squamous mucosa
Peripapillary IEL	IELs in the first five layers of squamous epithelium surrounding the esophageal papillae	Number of IELs per high-power field in the most densely infiltrated fields
Interpapillary IEL	IELs in the squamous epithelium beyond the peripapillary regions	Number of IELs per high-power field in the most densely infiltrated fields
Neutrophil	Neutrophils in squamous epithelium	Presence or absence
Eosinophil	Eosinophils in squamous epithelium	Number of eosinophils per high-power field in the most densely infiltrated fields
Columnar	Glandular epithelium	Presence or absence
Intestinal metaplasia	Goblet cells	Presence or absence
Glandular dysplasia	Neoplastic glandular epithelium confined above the basement membrane	Presence or absence
Subepithelial fibrosis	Increased collagen deposition underneath the epithelium	Presence or absence
Submucosal inflammation	Inflammatory cells in the submucosa	Presence or absence

IEL: intraepithelial lymphocytosis; IELs: intraepithelial lymphocytes.