User:Spikeandwave/Neonatal lupus erythematosus

Pathogenesis
Ro/SSA and La/SSB are proteins found inside cells. Antibodies against Ro/SSA and La/SSB can be seen in autoimmune diseases, the most common being Lupus and Sjögren’s. Mothers can present without clinical manifestations or a diagnosis of an autoimmune disease, but have anti-Ro antibodies with or without anti-La antibodies for the infant to be affected with neonatal lupus syndrome.

Maternal anti-Ro/SSA and anti-La/SSB antibodies can enter fetal circulation and affect neonatal organs by crossing the placenta using FcRn receptors. The mechanism in which the antibodies affect organs is not yet completely understood. For cardiac manifestations, it is proposed that these antibodies can bind to cells in the heart that go through physiologic cell death during embryogenesis. This leads to heart cell injury which causes secondary fibrosis in the conduction system, ultimately causing heart block. These antibodies can also affect calcium channels which are needed to initiate action potentials. Disruption to action potential propagation can affect the AV and SA nodes which are part of the conduction system of the heart.

Other factors like fetal susceptibility and environmental factors could also play a role in pathogenesis since not all infants develop congenital heart block even when exposed to antibodies.

Clinical Manifestations
Neonatal lupus can present in several ways. The most common manifestations involve the heart and skin.

Cardiac
Cardiac manifestations present more commonly in utero, but can also present after birth. The most common complications are varying degrees of heart block and endocardial fibroelastosis. Other anatomical defects have also been reported such as septal defects, valvular lesions, and patent ductus arteriosus. Bradycardia is a common initial finding in the prenatal period usually around the 2nd trimester.

Dermatological
A rash described as raised erythematous annular lesions can present upon delivery, but it can also become more visible later on after UV light exposure. The rash is commonly found on the head and face, but can also be found on other parts of the body. The rash is commonly seen around the eyes. The rash usually lasts 6-8 months when the maternal antibodies are no longer in circulation. Telangiectasia have also been seen and can occur with or without the annular rash.