INFECTIOUS ETIOLOGY OF XANTHOGRANULOMATOUS CHOLECYSTITIS : IMMUNOHISTOCHEMICAL IDENTIFICATION OF BACTERIAL ANTIGENS IN THE XANTHOGRANULOMATOUS LESIONS

The clinicopathologic features of 31 surgical patients with xanthogranulomatous cholecystitis were analysed in relation to the immunohistochemical demonstration of bacterial antigens using a polyclonal anti-E. coli antibody. The time period after the initial clinical manifestation was critical for identifying the bacterial antigens in the cytoplasm of foamy macrophages. Of 12 lesions removed within 4 weeks of the onset (subacute group), 7 lesions showed positive staining. No positivity was seen in 19 gall-bladder specimens with a clinical course of more than 4 weeks (chronic group). Abscess formation was seen in 7 cases in the subacute group, 5 of which were positive for the bacterial antigens. Gram-negative bacteria were cultured from the bile in four in the subacute group and three in the chronic group. All the four culture-positive subacute lesions were immunoreactive for the bacterial antigens. Accumulation of ceroid pigment in the cytoplasm of foamy macrophages was characteristically seen in 16 of 20 chronic lesions. Three subacute lesions with ceroid pigmentation was negative for the bacterial antigens. In conclusion, xanthogranulomatous cholecystitis can be divided into two forms: subacute and chronic, and the subacute form is closely related to bacterial infection.