WBR0403

Author	[[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Alison Leibowitz)(Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Dermatology, SubCategory::Musculoskeletal/Rheumatology
Prompt	[[Prompt::A 32-year-old man presents to the outpatient clinic for a pruritic skin lesion on his left elbow. He reports that the lesion has been present for several months, initially starting as a small area of erythema. On physical examination, you note a large plaque with overlying silvery scaling which bleeds when scraped off. An image of the patient’s lesion is displayed below. Which of the following findings is most likely to be associated with this patient's presentation? File:WBR0403.jpg]]
Answer A	AnswerA::Osteophyte formation
Answer A Explanation	[[AnswerAExp::Osteophyte formation is classically associated with osteoarthritis. Patients with psoriatic arthritis exhibit erosive changes in the small joints of the hands and feet on imaging.]]
Answer B	AnswerB::Tophus formation
Answer B Explanation	[[AnswerBExp::Tophus formation is seen in patients with longstanding and poorly controlled gout. Tophi are deposit of monosodium urate crystals in the joints, cartilage, and bones.]]
Answer C	AnswerC::Pannus formation
Answer C Explanation	[[AnswerCExp::Pannus formation is a complication of rheumatoid arthritis. Pannus is a layer of fibrovascular tissue that grows in the synovium and eventually erodes the surrounding articular cartilage and bone.]]
Answer D	AnswerD::Nail pitting
Answer D Explanation	[[AnswerDExp::Nail pitting is a key feature of psoriatic arthritis, a major complication seen in up to 10% of patients with psoriasis.]]
Answer E	AnswerE::Spider angiomata
Answer E Explanation	[[AnswerEExp::Spider angiomata, a form of telangiectasia, are frequently associated with cirrhosis. They result from the inability of the liver to metabolize excess circulating estrogens.]]
Right Answer	RightAnswer::D
Explanation	[[Explanation::Psoriasis is a T-cell mediated multisystem autoimmune disorder with pronounced dermatological manifestations. Classically, patients present with inflamed erythematous plaques on the scalp, trunk, and limbs with characteristic overlying silvery plaques that bleed when scraped off (Auspitz sign). Approximately 5 to 10% of patients with psoriasis develop clinically evident psoriatic arthritis during their lifetime. Psoriasis usually precedes arthritic manifestations, although psoriatic arthritis may be the presenting symptom in up to 20% of patients with psoriasis. Psoriatic arthritis is a seronegative arthritis that lacks rheumatoid factor positivity. Similarly to other forms of seronegative spondarthritides, psoriatic arthritis is also associated with HLA-B27. The disease manifests clinically as either asymmetric oligoarticular or symmetric polyarthritis. Other findings include dactylitis with "sausage digits", uveitis, and sacroiliitis. Nail involvement is extremely common in these patients and includes onycholysis, oil spots, and nail pitting. Educational Objective: Psoriasis is a T-cell mediated multisystem autoimmune disorder with pronounced dermatological manifestations. It is associated with psoriatic arthritis in 10% of patients, presenting as oligoarticular or symmetric polyarthritis, dactylitis, and nail pitting. References: Wilson FC, Icen M, Crowson CS, Mcevoy MT, Gabriel SE, Kremers HM. Incidence and clinical predictors of psoriatic arthritis in patients with psoriasis: a population-based study. Arthritis Rheum. 2009;61(2):233-9. Van Romunde LKJ, Hermans J, Valkenburg. Psoriasis and arthritis. Rheumatology International. 1984; 4(2):61-65]]
Approved	Approved::Yes
Keyword	WBRKeyword::arthritis, WBRKeyword::nail pitting, WBRKeyword::psoriasis, WBRKeyword::immune, WBRKeyword::immune disease, WBRKeyword::immune system, WBRKeyword::dermatology, WBRKeyword::psoriatic arthritis
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