WBR0745

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Hematology
Prompt	[[Prompt::A 4-year-old boy is brought by his mother to the emergency department for excessive fatigue and a yellowish tinge to his skin. Physical examination is remarkable for jaundice and a large palpable spleen on abdominal exam. Blood work-up reveals a low hematocrit, an elevated mean corpuscular hemoglobin concentration (MCHC), and increased bilirubin. A blood smear obtained from the patient is shown below. Which of the following findings is most consistent with this patient's condition? ]]
Answer A	AnswerA::Several family members with cholecystectomy
Answer A Explanation	[[AnswerAExp::Hereditary spherocytosis (HS) is an autosomal dominant genetic disorder characterized by the hemolysis and increased bilirubin that prediposes affected patients to gallbladder stones. Since the disease is autosomal dominant, a positive family history of HS is typical and thus a positive family history of cholecystectomy should raise the suspicion of HS in young patients presenting with jaundice and anemia.]]
Answer B	AnswerB::Personal history of macrosomia at birth
Answer B Explanation	AnswerBExp::Macrosomia is not associated with hereditary spherocytosis. The latter is a hereditary disorder.
Answer C	AnswerC::Maternal history of pre-eclampsia during pregnancy
Answer C Explanation	AnswerCExp::Pre-eclampsia does not predispose patients to hereditary spherocytosis. The latter is a hereditary disorder.
Answer D	AnswerD::Maternal use of amoxicillin during pregnancy
Answer D Explanation	AnswerDExp::Amoxicillin in considered safe in pregnancy.
Answer E	AnswerE::Recent history of fava bean intake
Answer E Explanation	AnswerEExp::Fava bean intake is associated with hemolysis in patients with G6PD deficiency.
Right Answer	RightAnswer::A
Explanation	[[Explanation::Hereditary spherocytosis (HS) is an autosomal dominant genetic disorder characterized by round, deformed red blood cells (RBC) due to red cell membrane defect. The RBC loses its biconcave shape and takes on a spherical shape that predisposes it to rupture and splenic sequestration. These RBC abnormalities are responsible for the clinical manifestations of the disease: anemia and jaundice secondary to the hemolysis, and splenomegaly secondary to sequestration of RBCs in the spleen. Blood work-up typically reveals low hemoglobin with elevated MCHC, and elevated levels of unconjugated bilirubin. Diagnosis of HS is by peripheral smear that shows the pathognomonic spherical RBCs. For most patients with HS, splenectomy is curative. Because HS is an autosomal dominant disorder, patients usually have a positive family history of the disease. In these patients, elevated bilirubin due to hemolysis predisposes to gallbladder stones that increase the risk of cholecystitis. As such, patients may present with a very positive family history of cholecystectomies. Educational Objective: Young patients presenting with jaundice, splenomegaly, and anemia with a positive family history for cholecystectomies should raise the suspicion for hereditary spherocytosis. References: Shah S, Vega R. Hereditary spherocytosis. Pediatr Rev. 2004;25(5):168-72.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Family history, WBRKeyword::Cholecystectomy, WBRKeyword::Hereditary spherocytosis, WBRKeyword::Anemia, WBRKeyword::Jaundice, WBRKeyword::Bilirubin, WBRKeyword::MCHC, WBRKeyword::Splenomegaly, WBRKeyword::Splenectomy, WBRKeyword::Autosomal dominant, WBRKeyword::Hemolysis, WBRKeyword::Hemolytic anemia, WBRKeyword::gallstones
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