WBR0780
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| 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 Blood withdrawn from patients with CREST syndrome doesn't agglutinate at cold temperatures.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. |
| 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:: |