WBR0780

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
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 with associated purplish discoloration of the tips. 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 is a possible explanation 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 Blood withdrawn from patients with CREST syndrome doesn't agglutinate at cold temperatures.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 a form of auto-immune hemolytic anemia caused by auto-antibodies to red blood cells that act at cold temperatures. It may either be a primary disease due to monoclonal antibodies, or secondary due to lymphoma, leukemia, EBV, CMV, HCV, Mycoplasma pneumoniae and several other infectious agents. The most common presenting symptom regardless of the underlying etiology is acrocyanosis (~40%). Acrocyanosis is defined as bluish-purplish discoloration of the distal fingertips and toes with cold exposure. Acrocyanosis may be associated with pain particularly in cold agglutinin disease. Other symptoms are specific to the underlying etiologies. Cold agglutinin disease presents more commonly in the winter months given its pathophysiology. Lab work-up may reveal 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. Educational Objective: Cold agglutinin disease is an autoimmune hemolytic anemia with cold-reactive antibodies to RBCs. It can occur in patients with M. pneumoniae infection. References: Swiecicki PL, Hegerova LT, Gertz MA. Cold agglutinin disease. Blood. 2013;122(7):1114-21.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Mycolplasma pneumoniae, WBRKeyword::Cold agglutinins, WBRKeyword::Auto-immune hemolytic anemia, WBRKeyword::Acrocyanosis
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::