Highlights of Section 4: Histopathology
ECCO statement 4AFor a reliable diagnosis of ulcerative colitis, a minimum of two biopsies from at least five sites around the colon [including the rectum] and the ileum should be obtained [EL 2]
ECCO statement 4BBiopsies should be accompanied by clinical information, including endoscopic findings, duration of disease and current treatment. Samples should be fixed immediately by immersion in buffered formalin or an equivalent solution before transport [EL 5]
4.3.1. Early stage disease
Not all the microscopic features found in UC are observed in early stage disease; only about 20% of patients show crypt distortion within 2 weeks of the first symptoms of colitis. The distinction from infectious colitis [acute self-limiting colitis], which is characterised by preserved crypt architecture and acute inflammation, is therefore a major concern.14,169
ECCO statement 4CBasal plasmacytosis is the earliest diagnostic feature with the highest predictive value for the diagnosis of ulcerative colitis [EL 3]. Preserved crypt architecture and the absence of a transmucosal inflammatory cell infiltrate do not rule out ulcerative colitis at an early stage. Repeat biopsies after an interval may help to solve differential diagnostic problems and establish a definitive diagnosis by showing additional features [EL 5]
Focal or diffuse basal plasmacytosis has been recognised as the earliest feature with the highest predictive value for UC diagnosis. It can be identified in 38% of patients within 2 weeks after symptoms presentation. During this period, the distribution pattern of basal plasmacytosis is focal, but may eventually change into a diffuse pattern throughout the disease course.250 Widespread mucosal or crypt architectural distortion, mucosal atrophy, and an irregular or villous mucosal surface appear later during the evolution of disease [at least 4 weeks after presentation].
ECCO statement 4DThe microscopic diagnosis of ulcerative colitis is based upon the combination of widespread crypt architectural distortion and mucosal atrophy, and a diffuse transmucosal inflammatory infiltrate with basal plasmacytosis, with active inflammation causing cryptitis and crypt abscesses [EL 2]
ECCO statement 4EA decreasing gradient of inflammation from distal to proximal favours a diagnosis of ulcerative colitis [EL5]. Treatment may change the classical distribution pattern of inflammation. Awareness of these treatment-related effects is important in the evaluation of biopsies from treated patients to avoid misdiagnosis [EL3]
ECCO statement 4FIn quiescent disease, the mucosa may still show features related to architectural damage and recovery, as well as disappearance of basal plasmacytosis and increased transmucosal cellularity. Active inflammation is usually not observed [EL 3]
ECCO statement 4GHistological healing is distinct from endoscopic mucosal healing. Histological inflammation may persist in cases with endoscopically quiescent disease and has been associated with adverse outcomes [EL2]
