[Risks of diagnostic errors in pathology research of post-abortion herpetic endometritis: limitations of immunohistochemistry in situ hybridization].

Endometrial Herpes-simplex infection is rare. Less than 10 cases have been reported. The impact of herpetic endometritis and abortion is not known, because of the scarcity of clinical and histological data. We present and discuss two cases of abortion with microscopic intranuclear inclusion of biotin, suggestive of herpetic endometritis. These inclusions were positively marked on immunohistochemistry, using anti-herpes antibodies. Similar results were obtained with in situ hybridization using biotin labeled probes (commonly used in some laboratories). But the normal accumulation of biotin in the endometrial cells of pregnant women diminishes the value of such results in gestational material. In fact the interaction between intranuclear endogenous biotin and the avidin-biotin-peroxidase complex may explain the positive controls, performed without anti-herpes antibodies. The biotin labeled probes may also explain the positive results of in situ hybridization. We strongly support the opinion that in pregnant women, the diagnosis of herpetic endometritis needs methodological precautions to avoid pitfall caused by endogenous biotin.