Figure 5

Propionibacterium acnes within sarcoid granulomas in the lymph node. Hematoxylin and eosin staining (left) and immunostaining with PAB antibody specific to Propionibacterium acnes (counterstained with hematoxylin) (right) are shown pairwise. (A, B) Square indicates an eosinophilic homogenous degenerated substance (hyaline-like degeneration). Positive reaction products (brown dots) are located preferentially in the hyaline-like degeneration (under×40 magnification objective). (C, D) In the sarcoid granuloma, a small positive dot is seen in an epithelioid cell (red arrow). Some fine reaction products are sparsely scattered in the sarcoid granuloma. A black arrow indicates a Langhans giant cell (under×40 magnification objective). Abbreviations: HE, hematoxylin and eosin; P., Propionibacterium.