Histological evaluation

Small Animal Section: No. 10

A GRADING SYSTEM FOR THE HISTOLOGICAL EVALUATION OF LYMPHOPLASMACYTIC ENTERITIS, a summary of the literature

Lymphoplasmacytic gastroenteritis is a relatively common disorder in dogs, less so in cats. The principle clinical signs are vomiting, small and large bowel diarrhoea, and weight loss. Once other causes of malassimilation have been ruled out, ie. exocrine pancreatic insufficiency, gastrointestinal biopsies are often submitted for further diagnosis. On biopsy it is possible to differentiate inflammatory bowel disease, infectious diseases, lymphangiectasia, and neoplasia.

In many cases, the cause of the inflammation is not clear, and the diagnosis of idiopathic inflammatory bowel disease (IBD) is made. Underlying hypersensitivity reactions are believed to occur, and the proposed initiating factors of IBD include defective immune regulation of gut-associated lymphoid tissue, infectious agents such as spiral organisms, genetic factors, biochemical abnormalities, psychosomatic disorders, permeability defects, dietary allergies and adverse drug reactions. In all cases, gastrointestinal inflammation is the final common pathway resulting in tissue damage.

These are the difficulties inherent in the evaluation of gastrointestinal biopsies:

	The small size of endoscopic biopsies taken from the gastrointestinal tract, which means that the biopsies may not be representative of the rest of the gut
	The evaluation of "what is normal" in terms of cell infiltrate into the various sections of the tract
	The lack of standardised criteria within the veterinary literature

It is for these reasons that we have decided to put forward a grading system, which we will use for evaluation of gastrointestinal biopsies based on the available literature.

The normal gastrointestinal mucosa is described as having a few lymphocytes and plasma cells present between glands and a few intraepithelial lymphocytes.

The key criteria used for grading lymphoplasmacytic gastroenteritis are the following:

	The density, distribution and extent of lymphocyte and plasma cell infiltration of the lamina propria; the predominant cell type; and the presence/absence of lymphangiectasia
	The height and shape of the superficial epithelium; density of intraepithelial lymphocytes and plasma cells; number and size of goblet cells; and the presence/absence of erosions or ulcerations.
	The height and width of intestinal villi; presence/absence of villus clubbing or fusion; numbers of crypts and glands; and presence/absence of obliteration of glands.
	Presence/absence of miscellaneous lesions such as hyperaemia, congestion, oedema, fibrosis, infectious agents and neoplasia.

GRADING :

The diagnosis of lymphoplasmacytic gastroenteritis, once made, needs to be qualified and graded in a manner, which is prognostically valuable to the clinician and meaningful in case comparisons/ follow up biopsies are performed. The use of symbols to grade pathological lesions enables us to evaluate cases in a manner which is useful and comparable. Both numerical and severity grades are given.

NORMAL (Grade 0-2):

Focal infiltrates of lymphocytes and plasma cells either present between 25-75% of glands, or diffusely with less than 3-4 cells in array between glands. The epithelium contains infrequent intraepithelial lymphocytes. No fibrosis, oedema or villous changes are present

MILD (Grade 2.5-3):

Mild diffuse to moderate focal lymphoplasmacytic infiltrates in the lamina propria (5 - 8 cells between glands). Normal columnar epithelium with mild increase in numbers of intraepithelial lymphocytes. Mild oedema and/or fibrosis may be present

MODERATE (Grade 3.5 – 4) :

Moderate diffuse to severe focal lymphoplasmacytic infiltrates in the lamina propria (> 8 cells between glands). Flattening of the absorptive epithelial cells with moderate numbers o intraepithelial lymphocytes. There may be decreased numbers of goblet cells; multifocal erosions; slight blunting of the villi; or a mild decrease in numbers of crypts and glands. Separation of glands or crypts by moderate cell infiltrates and/or fibrosis may have occurred. Moderate oedema and fibrosis may be present.

SEVERE (Grade 4.5-5):

Severe diffuse lymphoplasmacytic infiltrates in the lamina propria (> 8 cells between glands). Epithelial cells are cuboidal. Moderate numbers of intraepithelial lymphocytes, accompanied by a marked decrease in numbers of goblet cells and multifocal to coalescing erosions/ulcerations. Lymphangiectasia is frequently present and partial to complete obliteration of glands and crypts by cell infiltrates and/or fibrosis. Fusion and blunting of villi is also noted. Severe oedema and fibrosis is often present.

NOTE :

Lesions may vary considerably between biopsies and not all the pathological changes are necessarily present to the same degree as recorded in the grading system, in which case we use the most severe (pronounced) lesions for grading of the lymphoplasmacytic enteritis.

REFERENCES:

	Dennis, JS et al Lymphocytic/plasmacytic gastroenteritis in cats: 14 cases (1985-1990). Journal of the American Veterinary Medical Association 200: 11, 1712-1718
	Ettinger, SJ & Feldman EC Textbook of Veterinary Internal Medicine 5th Edition, Volume 2: Chapters 137 & 138 , 1182 - 1257
	Roth L et al, A grading system for lymphocytic plasmacytic colitis in dogs. Journal of Veterinary Diagnostic Investigation 2: 257 - 262 (1990)
	Guildford, W.G. Idiopathic inflammatory bowel diseases. Cht 24 in Strombeck’s Small Animal Gastroenterology, 3^rd Ed. Eds WG Guildford, SA Center, DR Strombeck, DA Williams, DJ Meyer,. W.B. Saunders, 1996

Compiled by dr Lorna Bolton and dr Emily Lane for VetPath

For further information contact:

VetPath Veterinary Pathologists
PO Box 8464, Pretoria 0001
Tel: (012) 529 8345/6
e-mail: info@vetpath.co.za

For any animal pathology queries, please send e-mail to info@vetpath.co.za.
Questions or comments about the structure of this web site, please send e-mail to webmaster@vetpath.co.za.
Copyright © 2004 Bill Robb & Associates
Last modified: Friday June 25, 2004