Is the immunohistochemical study of the inflammatory infiltrate helpful in distinguishing villitis of unknown etiology from non-specific infection villitis?

Abstract

Villitis is an important placental lesion, which can be caused by specific maternal infections, e.g. rubella, toxoplasmosis, etc, but most of them are of unknown etiology [1]. The clinical significance of villitis depends on the etiology and severity of fetal infection [2] and may lead to intrauterine fetal death, abortion, malformations and fetal growth retardation. The latter has been the major clinical association of villitis of unknown etiology (VUE) [2e4]. Morphologically, infectious villitis may show no specific features and can masquerade as VUE [5]. Both lesions are characterized by chronic inflammatory cells, mainly macrophages and lymphocytes, in the placental villous stroma [2,5]. There are few immunomorphological studies about the immune cells in infectious villitis as well as in VUE [6e9]. Labarrere et al. [6] described that in placentas with VUE the predominant inflammatory cells were activated macrophages expressing class II major histocompatibility complex antigens and helper T cells. Few CD8C T cells and no B cells were detected in the same lesions [6]. These findings contrast with those in villitis caused by maternal infection by Trypanosoma cruzi (Chagas’ disease), in which CD8C cells outnumbered CD4C T cells [7]. The aim of this study was to analyze whether immunohistochemical study of the inflammatory infiltrate in chronic villitis without specific morphological features could distinguish VUE from infectious villitis. All cases of villitis should be reported, particularly in developing countries, where there is a higher incidence of intrauterine infection [10] and the immunohistochemical study could provide objectivity that conventional histological methods lack.