WBR0872

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Musculoskeletal/Rheumatology
Prompt	[[Prompt::A 19-year-old girl presents to the emergency department for 2 days of severe abdominal pain involving mainly the upper quadrants. Although the pain started insidiously, it has become unbearable. She also decided to seek medical care because she started noticing blood in her stools. The patient denies consuming any food other than her home cooking. Upon further questioning, the patient reports recent onset articular pain she attributed to recent heavy exercise. On exam, the physician notes several findings including cervical lymphadenopathy, a nontender palpable purpuric rash in the lower extremities, and moderate nonpitting pedal edema. If the physician was to biopsy the patient's rash, which of the following findings would be expected on immunofluorescence?]]
Answer A	AnswerA::IgG, C3 and C4 deposits
Answer A Explanation	AnswerAExp::IgG, C3 and C4 deposits can be seen in the renal biopsies of patients with membranoproliferative glomerulonephritis. They are not seen in skin biopsies of patients with Henoch-Schönlein purpura.
Answer B	AnswerB::IgG, IgM, and C3 deposits
Answer B Explanation	AnswerBExp::IgG, IgM, and C3 deposits are not seen in skin biopsies of patients with Henoch-Schönlein purpura.
Answer C	AnswerC::IgE deposits
Answer C Explanation	AnswerCExp::IgE deposits are not seen in skin biopsies of patients with Henoch-Schönlein purpura.
Answer D	AnswerD::IgA and C3 deposits
Answer D Explanation	AnswerDExp::IgA and C3 deposits are classically seen in skin biopsies of the rash in patients with HSP. These deopsits are also seen in renal biopsies of patients with IgA nephropathy.
Answer E	AnswerE::IgA deposits
Answer E Explanation	AnswerEExp::IgA deposits without C3 are very rare due to the activation of the complement system by IgA.
Right Answer	RightAnswer::D
Explanation	[[Explanation::Henoch-Schönlein purpura (HSP) is a systemic disease characterized by vasculitis of the small vessels caused by immune deposits of IgA and C3 in arterioles, venules, and capillaries. Clinically the classic triad of HSP includes a skin rash mostly seen on the lower extremities and classically described as palpable purpura, arthralgias, and abdominal pain sometimes associated with vomiting, diarrhea, melena, or hematochezia. HSP is generally a pediatric disease although it can occur much less commonly in adults. HSP is closely related to IgA nephropathy as both diseases share a similar pathogenesis, with renal insufficiency being an important complication of HSP. In general, most cases are self-limited and only require supportive therapy. The abdominal pain usually subsides within a few days and most patients do not have recurrences. Educational Objective: Henoch-Schönlein purpura (HSP) is a systemic disease characterized by vasculitis of the small vessels caused by immune deposits of IgA and C3 often presenting with a triad of palpable purpura, abdominal pain, and arthralgia. References: Roberts PF, Waller TA, Brinker TM, Riffe IZ, Sayre JW, Bratton RL. Henoch-Schönlein purpura: a review article. South Med J. 2007;100(8):821-4.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Henoch-Schonlein Purpura, WBRKeyword::HSP, WBRKeyword::IgA, WBRKeyword::C3
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::