Case 137. E. coli-induced epididymitis (67 y-o M)
    Surgical resection for left epididymal tumor provoking active inflammatory response    
Key words : E. coli, epididymitis, xanthogranuloma, malakoplakia
The epididymal tissue has been destroyed by abscess formation (HE).   Xanthogranulomatous change is observed at the periphery of the abscess lesion. No epithelial structure remains any longer (HE).
E. coli antigens (lipopolysaccharides) are demonstrated in the cytoplasm of foamy cells (immunostaining). Infection by Gram-negative enteric bacteria is indicated.   Ultrastructurally, positivity of E. coli antigens in the xanthogranulomatous foamy cell corresponds to rod-like pathogens (pre-embedding immunoelectron microscopy using a paraffin section).
Reference case 137A
Malakoplakia of prostate (77 y-o M). Needle biopsy shows diffuse foamy cell infiltration. A few Michaelis-Guttmann bodies are discerned (HE). Differential diagnosis from poorly differentiated adenocarcinoma is needed. Malakoplakia and xanthogranulomatous inflammation are closely related each other.
  Reference case 137A
Localization of E. coli antigens in the cytoplasm of foamy cells and Michaelis-Guttmann bodies (immunostaining). Immunostaining for E. coli antigens (LPS) using a DakoCytomation's commercial antiserum is valuable not only to confirm the diagnosis but also to clarify the etiology of the lesion.