WBR0750

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 62-year-old woman presents to the physician's office with complaints of of muscle weakness for the past 3 weeks. She states that she has recently been unable to comb her hair or stand from a seated position. When asked, she says that she has no difficulty buttoning shirts. Review of systems is remarkable for arthralgia that involves the hand joints, wrists, and knees. Inspection of the patient's face shows periorbital violaceous erythema with edematous eyelids. Physical examination is remarkable for symmetric proximal muscle weakness. Further evaluation of her dorsal interphalangeal and metacarpophalangeal joints reveals violaceous flat-topped papules and plaques. Lab work-up is remarkable for elevated concentration of creatine kinase. What is the histopathological feature of this patient's condition?]]
Answer A	AnswerA::Endomysial inflammation
Answer A Explanation	AnswerAExp::Endomysial inflammation is characteristic of polymyositis.
Answer B	AnswerB::Perimysial inflammation
Answer B Explanation	AnswerBExp::Perimysial inflammation is characteristic of dermatomyositis.
Answer C	AnswerC::Non-caseating granulomas
Answer C Explanation	AnswerCExp::Non-caseating granulomas are commonly observed in sarcoidosis.
Answer D	AnswerD::Precipitation of monosodium urate crystals
Answer D Explanation	AnswerDExp::Precipitation of monosodium urate crystals is characteristic of gout.
Answer E	AnswerE::Autoimmune inflammatory destruction of synovial joints
Answer E Explanation	AnswerEExp::Rheumatoid arthritis (RA) is characterized by the autoimmune inflammatory destruction of synovial joints.
Right Answer	RightAnswer::B
Explanation	[[Explanation::Dermatomyositis is an inflammatory myopathy characterized by symmetric proximal and truncal weakness with or without associated pain. Physical examination is typically remarkable for Gottron papules (violaceous flat-topped papules and plaques in the dorsal aspect of the hand) and characteristic heliotrope rash (periorbital violaceous erythema with periorbital edema). Work-up often demonstrates elevation of muscle biomarkers, such as creatine kinase. Pathologically, dermatomyositis is considered a perimysial inflammation with lymphocytic infiltration that is generally confined to the septa. Dermatomyositis has a bi-modal peak incidence. In adult patients > 50 years of age, the diagnosis of dermatomyositis prompts the investigation of a malignancy due to frequent association. This is not true, however, for those diagnosed at young age. Educational Objective: Dermatomyositis is characterized by perimysial inflammation. References: Khan S, Christopher-Stine L. Polymyositis, dermatomyositis, and autoimmune necrotizing myopathy: clinical features. Rheum Dis Clin N Am. 2011; 37:143-158.<br Dalakas M. Polymyositis, dermatomyositis, and inclusion-body myositis. N Engl J Med. 1991; 325:1487-1498. First Aid 2014 page 429.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Dermatomyositis, WBRKeyword::Myopathy, WBRKeyword::Inflammatory, WBRKeyword::Proximal muscle weakness, WBRKeyword::Perimysial inflammation, WBRKeyword::Endomysial inflammation, WBRKeyword::Gottron papules, WBRKeyword::Heliotrope rash
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::