This is the typical microscopic appearance of an actinobacillosis
granuloma. It consists in an eosinophilic central area, called sulphur
granule, (formed by the pathogen and by immune complexes synthesized as
a response to the infection) enclosed in a neutrophilic cellular atmosphere.
Peripherally, several mononuclear cellular elements can be found, namely
macrophages, plasmocytes and lymphocytes (H&E, 100x). This inflammatory
response causes a fibroblastic reaction that progressively isolates the
granuloma from the surrounding tissue. On the right, radiated structures
arranged in palisade, called clubs, form the periphery of the sulphur
granule (H&E, 400X).
Copyright © 2001 by MC
Peleteiro. M Pinho & JS Orvalho
design by R Noiva