WBR0111

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics
Sub Category	SubCategory::Dermatology, SubCategory::Hematology
Prompt	[[Prompt::A 23-year-old woman presented to her primary care physician complaining of the appearance of small red lesions on her lips, nose and fingers. The patient reports that these lesions have appeared rather suddenly, many arising over the past year.  Her past medical history is significant for nosebleeds and severe gastrointestinal distress since childhood.  The patient confirms that she has seen black stools that tend to accompany her gastrointestinal distress. Laboratory studies reveal the following pH: 7.41 WBC: 2,400 /mm3 Platelets: 200,000 /mm3 Hemoglobin: 6.2 g/dL Ferritin: 4.32 (13-150ng/mL) Serum iron: 36 (50-150 ug/dL) Albumin: 3.5 g/dL Which of the following conditions is most likely in this patient?]]
Answer A	AnswerA::Henoch-Schonlein Purpura
Answer A Explanation	[[AnswerAExp::Incorrect – Henoch-Schonlein purpura is a small-vessel vasculitis caused by IgA immune complex deposition in blood vessels. The syndrome commonly causes kidney disease, abdominal pain, joint pain and palpable purpura (usually of the legs). HSP is not characterized by recurrent epistaxis, nor telangiectasias of the lips, nose and fingers.]]
Answer B	AnswerB:: Von-Willebrand's Disease
Answer B Explanation	[[AnswerBExp::Incorrect – Von Willebrand’s disease is the most common hereditary coagulation abnormality. It is caused by a deficiency of von Willebrand protein, a multimeric protein required for platelet adhesion. Patients often experience recurrent epistaxis, easy bruising and bleeding gums. Telangiectasias of the lips, fingers and nose are not a hallmark of this disease, nor is gastrointestinal bleeding.]]
Answer C	AnswerC::Osler Weber Rendu Syndrome
Answer C Explanation	AnswerCExp::Correct – See Explanation
Answer D	AnswerD::Factor VIII Deficiency
Answer D Explanation	AnswerDExp::Incorrect – Factor VIII Deficiency is the cause of Hemophilia A, an X-linked recessive clotting disorder. Patients with hemophilia suffer severe bleeds.
Answer E	AnswerE::Thrombotic thrombocytopenic purpura
Answer E Explanation	[[AnswerEExp::Incorrect – Thrombotic thrombocytopenia purpura is a rare disorder of the blood-coagulation system, causing extensive microscopic clots to form in the small blood vessels throughout the body. Patients with TTP may have nosebleeds due to consumption of platelets in widespread thrombus formation. However, TTP is often sudden in onset, and does not cause telangiectasias of the lips, nose and fingers.]]
Right Answer	RightAnswer::C
Explanation	[[Explanation::The patient in this vignette suffers from Osler-Weber-Rendu syndrome (also known as Hereditary Hemorrhagic Telangiectasia, HHT). Her recurrent epixstasis, characteristic talgiectasias, and anemia due to gastrointestinal bleeding highly suggest the diagnosis. Hereditary hemorrhagic telangiectasia is a genetic disorder that leads to abnormal blood vessel formation in the skin, mucous membranes, and often in organs such as the lungs, liver, and brain. It may lead to nosebleeds, acute and chronic digestive tract bleeding, and various problems due to the involvement of other organs. Treatment focuses on reducing bleeding from blood vessel lesions, and sometimes surgery or other targeted interventions to remove arteriovenous malformations in organs. Chronic bleeding often requires iron supplementsand sometimes blood transfusions. HHT is transmitted in an autosomal dominant fashion, and occurs in one in 5,000 people. Educational Objective: Hereditary Hemorrhagic Telangiectasia (Osler Weber Rendu Syndrome) is characterized by recurrent epixstasis, telangiectasias, and gastrointestinal bleeding. References: First Aid 2012 page 90. Tags: #Genetics #Hematology Educational Objective: References: ]]
Approved	Approved::Yes
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