WBR0780

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology, MainCategory::Pathophysiology
Sub Category	SubCategory::Hematology
Prompt	[[Prompt::A 37 year old woman presents to her primary care physician for painful fingers tips associated with purplish discoloration. The patient started to notice the symptoms early in the winter especially after her central heating system broke down. The physician decides to work the patient up and withdraws blood in a heparin tube to send for testing. Several minutes after withdrawal the physician notices that the patient’s blood had started to clump. Which of the following can be a possible explain for the patient’s condition?]]
Answer A	AnswerA::CREST syndrome
Answer A Explanation	AnswerAExp::CREST syndrome is associated with Raynaud's phenomenon that can resemble acrocyanosis but Raynaud's is usually a triphasic color change. Blood withdrawn from patients with CREST syndrome doesn't agglutinate at cold temperatures.
Answer B	AnswerB::M. tuberculosis infection
Answer B Explanation	AnswerBExp::M. tuberculosis infection is not associated with cold agglutinin disease.
Answer C	AnswerC::Septic emboli
Answer C Explanation	AnswerCExp::Septic emboli can cause purplish discoloration of the fingers and toes, however the patient would have a different presentation.
Answer D	AnswerD::M. pneumoniae infection
Answer D Explanation	AnswerDExp::Mycoplasma pneumoniae infections can be associated with cold agglutinin auto-immune hemolytic anemia.
Answer E	AnswerE::Tumor lysis syndrome
Answer E Explanation	AnswerEExp::Tumor lysis syndrome is not associated with cold agglutinin disease.
Right Answer	RightAnswer::D
Explanation	[[Explanation::Cold agglutinin disease is an auto-immune hemolytic anemia caused by autoantibodies to red blood cells that at at cold temperatures. It may either be a primary disease with monoclonal antibodies, or secondary to lymphoma, leukemia, EBV, CMV, HCV, Mycoplasma pneumoniae and several other infectious agents. The common presenting symptom of most patients regardless of the underlying etiology is acrocyanosis (~40%). Acrocyanosis defines symptoms of painful fingers and toes associated with bluish-purplish discoloration usually during cold exposure. Cold agglutinin disease is more common to present in the winter months given the pathophysiology. Other symptoms are specific to the underlying etiologies. Lab work-up would show anemia, reticulocytosis, elevated LDH and bilirubin, with decrease in haptoglobin. Cold agglutinin titers can also be tested. Titers can be so elevated that RBCs agglutinate even in anticoagulated blood samples at lower room temperatures. Learning objective: Cold agglutinin disease is an autoimmune hemolytic anemia with cold-reactive antibodies to RBCs. It can occur in patients with M. pneumoniae infection. Reference: Swiecicki PL, Hegerova LT, Gertz MA. Cold agglutinin disease. Blood. 2013;122(7):1114-21. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Mycolplasma pneumoniae, WBRKeyword::Cold agglutinins, WBRKeyword::Auto-immune hemolytic anemia, WBRKeyword::acrocyanosis
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