Clinical and pathologic implications of extending the spectrum of maternal autoantibodies reactive with ribonucleoproteins associated with cutaneous and now cardiac neonatal lupus from SSA/Ro and SSB/La to U1RNP

Abstract

While the relationship between maternal connective tissue diseases and neonatal rashes was described in the 1960s and congenital heart block in the 1970s, the "culprit" antibody reactivity to the SSA/Ro-SSB/La ribonucleoprotein complex was not identified until the 1980s. However, studies have shown that approximately 10-15% of cases of congenital heart block are not exposed to anti-SSA/Ro-SSB/La. Whether those cases represent a different disease entity or whether another antibody is associated has yet to be determined. Moreover, the cutaneous manifestations of neonatal lupus have also been identified in infants exposed only to anti-U1RNP antibodies. In this review, we describe what we believe to be the first case of congenital heart block exposed to maternal anti-U1RNP antibodies absent anti-SSA/Ro-SSB/La. The clinical and pathologic characteristics of this fetus are compared to those typically seen associated with SSA/Ro and SSB/La. Current guidelines for fetal surveillance are reviewed and the potential impact conferred by this case is evaluated.

Keywords: Antibodies; Congenital heart block; Neonatal lupus.

Figure 1

A – Low-power view of the bundle of His (circled) demonstrating myocyte loss, scarring and calcification confined to the conducting system (100x original magnification, hematoxylin & eosin). B – Higher-power view of the conducting system showing calcified remnants of myocytes (arrows) and dense collagen (200x, H&E) C – High-power view of the AV nodal tissue showing no evidence of pathology in this location (200x H&E). D – Focal areas of myocyte calcification of the non-conducting septal myocardium were appreciated (200x, H&E).