WBR0882

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathophysiology, MainCategory::Pharmacology
Sub Category	SubCategory::Vascular, SubCategory::Infectious Disease
Prompt	[[Prompt::A 42-year-old man presents to the rheumatology clinic for several weeks of fatigue, weight loss, and generalized arthralgias. He initially did not pay much attention to his symptoms until he started losing sensation in both his lower extremities. His history is otherwise unremarkable. On physical examination, the physician notices several cutaneous nodules of different sizes on the patients arms and proximal legs. He also notes significant sensory loss below the knees bilaterally. Faced with a difficult clinical presentation, the physician decides to biopsy the skin nodules. The pathologist reading the specimen describes significant transmural fibrinoid necrosis of blood vessels with lesions of different ages seen on the same biopsy specimen. Which of the following clinical tests should be considered in this patient?]]
Answer A	AnswerA::Bronchoscopy with biopsy for lung involvement
Answer A Explanation	AnswerAExp::PAN typically spares the pulmonary parenchyma so bronchoscopy with biopsy is not indicated.
Answer B	AnswerB::Peripheral blood smear and reticulocyte count
Answer B Explanation	AnswerBExp::Although a peripheral blood smear and a reticulocyte count can be helpful in ruling out other diagnoses, with the biopsy showing typical signs of PAN they would not be of great benefit.
Answer C	AnswerC::Hepatitis B Antigen testing and serologies
Answer C Explanation	AnswerCExp::Hepatitis B surface antigen and hepatitic C serologies should be considered in all patients with PAN due to the association between hepatitis and the development of PAN.
Answer D	AnswerD::Abdominal aortogram for aortic involvement
Answer D Explanation	AnswerDExp::PAN is a medium-vessel vasculitis that spares large vessels such as the aorta. Takayasu's arteritis usually involves large vessels.
Answer E	AnswerE::Coronary arteriogram for coronary artery involvement
Answer E Explanation	AnswerEExp::PAN is not associated with coronary artery vasculitis. Classically, the coronary arteries are involved in Kawasaki disease and may develop aneurysms.
Right Answer	RightAnswer::C
Explanation	[[Explanation::Polyarteritis nodosa (PAN) is a systemic illness characterized by medium-vessel vasculitis involving vessels of the kidneys, gastrointestinal tract, skin, nerves, joints, and muscles sparing the lungs. Pathologically, PAN is described as a transmural necrosis of medium-sized vessels with lesions of varying age leading to a disruption of visceral blood flow and ischemia. Patients with PAN usually present with constitutional symptoms with associated symptoms related to the involved organ systems. Patients can have some form of neurologic impairment, skin changes including rashes and nodules, abdominal pain and GI bleeding, as well as symptoms related to renal impairment. PAN can be idiopathic in many patients; however, both hepatitis B and hepatitis C have been linked to its development. Hepatitis B positivity can be seen in up to a quarter of patients with PAN. Treatment includes corticosteroids mainly combined with cyclophosphamide in certain cases. Educational Objective: PAN is a medium vessel vasculitis characterized by transmural fibrinoid necrosis, classically associated with hepatitis B infection. References: Pettigrew HD, Teuber SS, Gershwin ME. Polyarteritis nodosa. Compr Ther. 2007;33(3):144-9.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Polyarteritis nodosa, WBRKeyword::PAN, WBRKeyword::Hepatitis B
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