Pathologica 4-07.pdf - Pacini Editore

PATHOLOGICA 2007;99:117
Patologia infiammatoria intestinale
Tavola rotonda: le diagnosi inutili, coliti non IBD,
malattia celiaca
What is Colitis? Infections and IBD
K. Geboes
Department of Pathology, KU Leuven, Belgium
The prevalence of diarrhea number of individuals with a specific
condition at a given time is approximately 5%, making
it a major cause of disability. Patients with chronic diarrhea,
with or without the passage of blood, are likely to be fully investigated,
inclusive one or other form of endoscopy with
biopsy. A study evaluating more than 800 patients with
chronic diarrhea found that 122 15% of them had abnormal
histopathology. Histological diagnoses include a variety of
conditions such as spirochetosis, pseudomelanosis coli and
microscopic colitis. Various forms of colitis can thus be present
in the absence of radiological and endoscopic lesions or
features of colitis. In the absence of clinical information, a
mere increase in predominantly chronic inflammatory cells
beyond what would be expected physiologically in the absence
of architectural abnormalities with or without reactive
changes in the surface epithelium reduced height of cells and
in the crypts increase in mitoses and slight irregularity in
shape can only be diagnosed as “non-specific colitis”. This
pattern can be seen in resolving infections, diverticular disease,
drug-induced colitis and even Crohn’s disease. However,
lack of sufficient clinical data and distinctive histopathological
features precludes further classification into specific
types of colitis. Various entities can mimic chronic inflammatory
bowel disease. A diagnosis is optimally reached when
the histological findings can be combined with clinical information
although there are many conditions where histology
on its own may be sufficient.
Microscopic examination of biopsies is important for the diagnosis
of inflammation. A proper diagnosis requires multiple
biopsies. The first question to be answered by the pathologist
analysing biopsy specimens is whether there are signs
of inflammation. Genuine inflammation has to be distinguished
from artefacts and implies the presence of alterations
of epithelial cells and lamina propria cellularity.
Infectious type colitis, also called Acute self-limited colitis
ASLC, is a transient, presumably infectious disorder presenting
with the sudden onset of bloody diarrhea, which may mimic
IBD. A precise diagnosis is especially needed in the case of
a severe first attack for which steroid treatment or surgery is
contemplated. Stool cultures take 48-72 h and grow pathogens
in only 40-60%. Rectal biopsies are the major tool for the differential
diagnosis between ASLC and Crohn’s disease and/or
ulcerative colitis. In terms of pathology acute inflammation is
usually signaled by the exudation into the tissue of neutrophils
and chronic inflammation is characterized by increased lymphocytes,
plasma cells and macrophages in the affected tissue.
B lymphocytes are transformed into mature plasma cells becoming
visible in abundance after 7 to 10 days following the
initial inflammatory response.
Major discriminating parameters for IBD are architectural
abnormalities such as a pseudovillous or villiform mucosal
surface, a disturbed crypt architecture, mucosal atrophy,
basal plasmacytosis, and epithelioid granulomas. The distribution
of the inflammatory infiltrate can also orient towards
a diagnosis of infectious type colitis. In this type of colitis the
inflammatory reaction is mainly situated in the upper third of
the lamina propria. The presence of crypt abscesses is not a
reliable feature for the distinction between IBD and infectious
type colitis.