[Biopsy differential diagnosis of non-cancerous small intestinal diseases]

Both pathologists and gastroenterologists are one team working up patients with suspected small bowel diseases. Both have to try to recognize the various entities of disorders found in the small bowel. Some diseases, such as Whipple's disease, are histologically easily recognized by their specific changes. Others, however, show unspecific histological changes and may only be recognized by a certain pattern of inflammatory infiltration of the mucosa and/or by architectural changes. In the present paper giardiasis with its diagnostic trophozoites, Crohn's disease and celiac disease with their typical inflammation and mucosal architecture and their differential diagnoses are discussed. A modified Marsh classification is given, which allows to report the various types of celiac lesions more precisely. Furthermore, the variations found in the normal mucosa are presented. In particular, the presence of lymphocytes and plasma cells in the lamina propria is shown to be a part of the mucosa associated lymphatic tissue (MALT). The importance of giving a clear statement on the etiology of the disease whenever possible is stressed.