WBR0190
| Author | [[PageAuthor::Mahmoud Sakr M.D. (Reviewed by Yazan Daaboul, M.D.)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Immunology, MainCategory::Pathophysiology |
| Sub Category | SubCategory::Musculoskeletal/Rheumatology |
| Prompt | [[Prompt::A female neonate with severe bradycardia is rushed to the operating room for pacemaker placement. She is born to a 25-year-old African-American mother who has a medical history significant for an autoimmune disease with chronic joint pains, malar rash, and photosensitivity. Upon further investigation, the mother admits she has not received any prenatal care. Physical examination of the neonate is remarkable for severe bradycardia and presence of erythematous annular lesions with central clearing and raised red borders on the face and the scalp. An ECG prior to the procedure reveals a complete dissociation between the P waves and the QRS complexes. Screening for which auto-antibodies in the mother could have prevented this patient's condition?]] |
| Answer A | AnswerA::Anti-Ro antibodies |
| Answer A Explanation | AnswerAExp::Neonatal lupus (NL) results from the transplacental passage of maternal anti-SSA/Ro and/or anti-SSB/La antibodies. |
| Answer B | AnswerB::Anti-RNP antibodies |
| Answer B Explanation | AnswerBExp::Anti-RNP antibodies are autoantibodies associated with mixed connective tissue disease and are also detected in nearly 40% of patients with SLE. However, they're not classically associated with NL |
| Answer C | AnswerC::Anti-double-stranded DNA (dsDNA) antibodies |
| Answer C Explanation | AnswerCExp::Anti-dsDNA antibodies are very specific for SLE and are therefore used in the diagnosis of SLE. However, they are not the most common type of autoantibodies associated with NL |
| Answer D | AnswerD::Anti-ribosomal P protein antibodies |
| Answer D Explanation | AnswerDExp::Anti-ribosomal P protein antibodies are autoantibodies present in a minority of patients with SLE. They are highly specific for SLE, not NL |
| Answer E | AnswerE::Antiphospholipid antibodies |
| Answer E Explanation | AnswerEExp::Antiphospholipid syndrome is an autoimmune disease caused by antiphospholipid autoantibodies. APS is a hypercoagulable state and results in arterial and venous thrombosis and pregnancy-related complications, such as recurrent miscarriages. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Neonatal lupus is a relatively rare disease of the newborn characterized by cutaneous lesions and third-degree heart block, along with dilated cardiomyopathy, hepatobiliary disease, and hematological abnormalities. Although cutaneous lupus lesions often appear several days later, patients may develop lesions immediately after birth. The lesions are typically described similarly to those described in this patient, showing annular erythema with central clearing and raised red borders. Classically, congenital third-degree (complete) heart block begins in utero and persists antenatally. On ECG, third-degree heart appears as a complete dissociation between the P waves and the QRS complexes. The presence of heart block has been attributed to fibrosis of the AV node region. Patients usually require pacemaker placement, and if left untreated, the majority of patients die.
Neonatal lupus is responsible for 80 to 95% of all cases of congenital complete heart block diagnosed in utero or in the neonatal period. The characteristic skin rash, the maternal history consistent with systemic lupus erythematosus (autoimmune disease characterized by joint paints, malar rash, and photosensitivity in an African-American patient), and the congenital heart block makes the diagnosis of neonatal lupus very likely. Neonatal lupus (NL) results from the transplacental passage of maternal anti-SSA/Ro and/or anti-SSB/La antibodies. The presence of anti-Ro-antibodies is considered the most significant risk factor for the development of neonatal lupus. Most infants with complete heart block have a mother with anti-SSA/Ro and anti-SSB/La antibodies, and screening for those antibodies may prevent the patient's condition by administration of systemic corticosteroids, which has demonstrated efficacy in improving outcomes in neonatal lupus. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Lupus, WBRKeyword::Neonatal lupus, WBRKeyword::Systemic lupus erythematosus, WBRKeyword::Autoimmune, WBRKeyword::Autoantibody, WBRKeyword::Systemic lupus erythematosus, WBRKeyword::SLE, WBRKeyword::Congenital heart block, WBRKeyword::Third degree heart block, WBRKeyword::Complete heart block |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |