Twin Presentation of Cutaneous Neonatal Lupus Associated With Maternal Anti-U1RNP Antibodies: A Case Report.

Neonatal lupus erythematosus (NLE) is a rare autoimmune condition caused by the transplacental transfer of maternal IgG autoantibodies, most commonly anti-Sjögren's-syndrome-related antigen A (anti-Ro/SSA) and anti-Sjögren's-syndrome-related antigen B (anti-La/SSB). NLE associated solely with anti-U1RNP antibodies is uncommon and typically limited to cutaneous manifestations, with extremely few cases reported in twins. We describe bi-chorionic bi-amniotic preterm twin girls who developed atypical erythematous lesions along the trajectory of epicutaneo-cava catheters during the second week of life. Autoimmune screening revealed strongly positive anti-U1RNP antibodies in both infants; cardiac evaluation was normal. Autoantibodies became negative by eight months. Both twins showed normal development and no further manifestations at 15 months. Maternal evaluation uncovered previously unrecognized antinuclear antibody (ANA) and anti-ribonucleoprotein antibody(anti-RNP) positivity. This appears to be the first reported case of anti-U1RNP NLE presenting with catheter-aligned inflammatory lesions in twins. The case highlights the role of trauma-induced Koebnerization as a potential trigger and underscores the importance of considering autoimmune etiologies in synchronous neonatal skin lesions, as well as the value of neonatal findings in identifying occult maternal autoimmunity.