A newborn develops annular erythematous plaques on the face and scalp at 3 weeks of age. ECG shows complete atrioventricular block. The mother reports a photosensitive rash during pregnancy. Which maternal antibody is responsible?
- A Anti-La/SSB alone
- B Anti-U1 RNP
- C Anti-Ro/SSA with or without anti-La/SSB ✓
- D Anti-histone antibodies
Correct answer: C. Anti-Ro/SSA with or without anti-La/SSB
Explanation
Neonatal lupus results from transplacental passage of maternal IgG anti-Ro/SSA, often with anti-La/SSB. Cutaneous lesions are annular and photosensitive and resolve as maternal antibody clears, but cardiac involvement can be permanent. Anti-U1 RNP defines mixed connective tissue disease, and anti-histone antibodies point to drug-induced lupus, neither of which causes congenital heart block.
Reference: Fitzpatrick's Dermatology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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