Necrotizing funisitis and herpes simplex infection of placental and decidual tissues: study of four cases.

Necrotizing funisitis (NF) is a macroscopically and microscopically distinctive pattern of umbilical cord inflammation recently heralded as presumptive of congenital syphilis. Four nonsyphilitic cases are presented in which herpes simplex virus (HSV) 2 antigen was demonstrated in the placenta by immunohistochemistry. The clinicopathologic findings in one case, including HSV 2 antigen in amniotic epithelium, subamniotic chorion, and Wharton jelly, indicate that NF was caused by chronic ascending primary HSV 2 infection, whereas those of the other three cases with HSV 2 Ag confined to decidual cell clusters suggest that NF was caused by chronic ascending bacterial infection and that latent endometrial HSV 2 infection was fortuitous. We conclude that (1) NF is caused by protracted inflammation of a structure whose normal anatomy precludes removal of inflammatory debris; (2) no single pathogen causes NF; and (3) NF is strongly associated with latent endometrial HSV 2 infection, which should be sought in all instances. Although latent HSV 2 endometrial infection may be more prevalent than currently recognized, we speculate that its strong association with NF may be more than causal; whereas the usual ascending bacterial infection leads to labor before NF has had sufficient time to develop, latent endometrial HSV 2 infection may alter local paracrine factors and delay parturition for the time sufficient to permit NF, a morphological hallmark of chronicity, to become apparent.