[Biopsy diagnosis of diseases of the small intestine].

Bioptical diagnosis of disease of the small intestine is shortly reviewed. Different methods of morphological investigations are described (lens microscopy, light microscopy, immunohistology, histochemistry, electron microscopy). A classification is proposed of pathological changes of the mucosa from the point of view of pathogenesis as well as from the point of view of practical diagnosis. In daily routine diagnostic procedures biopsies from the small intestine should be investigated with the lens microscope and with the light microscope. Both procedures are suited to answer diagnostic questions in most cases sufficiently. The other methods mentioned are usually not needed for routine diagnosis. Immunohistology (immunofluorescence, enzymatic immune histochemistry) does have importance in diagnosis of pathological conditions caused by defect of certain immunoglobulins.