WBR0752

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Musculoskeletal/Rheumatology
Prompt	[[Prompt::A 27-year-old man with no past medical history presents to the physician's office for recurrent left knee pain. The patient explains that he has recently received antibiotics to treat a urethral infection 2 weeks ago. He reports his knee pain does not involve his right knee and is moderately relieved with administration of naproxen. Work-up is remarkable for elevated concentration of C-reactive protein (CRP) and a markedly elevated HLA-B27 surface antigen. Which of the following findings on physical examination is most associated with this patient's condition?]]
Answer A	AnswerA::Conjunctival redness
Answer A Explanation	AnswerAExp::Manifestations of reactive arthritis are summarized by the classic triad of conjunctivitis, urethritis, and arthritis.
Answer B	AnswerB::Systolic ejection murmur
Answer B Explanation	AnswerBExp::Aortic stenosis is not common among patients with reactive arthritis. However, ankylosing spondylitis, also a seronegative spondyloarthropathy, is associated with aortic regurgitation.
Answer C	AnswerC::Facial rash that spares the nasolabial folds
Answer C Explanation	AnswerCExp::Malar rash is characteristic of systemic lupus erythematosus.
Answer D	AnswerD::Violaceous eruption on the upper eyelids
Answer D Explanation	AnswerDExp::Heliotrope rash is characteristic of dermatomyositis.
Answer E	AnswerE::Excoriated papules on the dorsum of the hands
Answer E Explanation	AnswerEExp::Skin excoriation is not associated with reactive arthritis.
Right Answer	RightAnswer::A
Explanation	[[Explanation::Reactive arthritis (ReA or Reiter's syndrome) is an autoimmune inflammatory arthritis. Infection with either Chlamydia, Salmonella, Shigella, or Campylobacter is strongly associated with the development of ReA. ReA typically manifests with mono-inflammatory, non-migratory, arthritic pain 2 to 4 weeks following a gastrointestinal or a urethral infection. Laboratroy findings are usually unremarkable except for elevated concentrations of acute phase reactants, such as CRP and ESR. ReA is a subtype of seronegative spondyloarthropathies (arthritis with negative RF) that is associated with HLA-B27 class I surface antigen. The classic triad of ReA manifestations is conjunctivitis, urethritis, and arthritis [Mnemonic: Can't see (conjunctivitis), can't pee (urethritis), can't climb a tree (arthritis)]. The diagnosis of ReA is clinical, and treatment includes NSAIDs for symptomatic relief in most of the cases until the pain self-resolves. However, rare refractory cases might require either intra-articular, systemic steroids, or disease-modifying antirheumatic drugs (DMARDs). Common HLA subtypes and their associated diseases are shown in the table below. Educational Objective: Reactive arthritis (ReA or Reiter's syndrome) is an autoimmune inflammatory arthritis. Infection with either Chlamydia, Salmonella, Shigella, or Campylobacter is strongly associated with the development of ReA. ReA typically manifests with mono-inflammatory, non-migratory, arthritic pain 2 to 4 weeks following a gastrointestinal or a urethral infection. Reactive arthritis manifestations are the triad of conjunctivitis, urethritis, and arthritis. References: Kim PS, Klausmeier TL, Orr DP. Reactive arthritis: a review. J Adolesc Health. 2009;44(4):309-15. First Aid 2014 page 426]]
Approved	Approved::Yes
Keyword	WBRKeyword::Reactive arthritis, WBRKeyword::Seronegative spondyloarthropathies, WBRKeyword::HLA-B27, WBRKeyword::HLA subtypes, WBRKeyword::Conjunctival redness, WBRKeyword::Conjunctivitis, WBRKeyword::Urethritis, WBRKeyword::Arthritis, WBRKeyword::Autoimmune, WBRKeyword::Inflammatory arthritis
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