Clinical History:
- A 29-year-old woman with a diagnosis of acute promyelocytic leukemia has developed petechiae and ecchymoses over the skin of her trunk and extremities in the past 3 days. On physical examination her vital signs include temperature 37.2 C, pulse 101/minute, respirations 19/minute, and blood pressure 85/45 mm Hg. Laboratory studies include a CBC showing Hgb 8.7 g/dL, Hct 24.5%, MCV 85 fL, platelet count 17,000/microliter, and WBC count 8700/microliter.
- What is the prominent finding on her peripheral blood smear?
The peripheral blood smear demonstrates many fragmented RBC's (schistocytes).
- What is the diagnosis from these findings?
Microangiopathic hemolytic anemia, in this case disseminated intravascular coagulation (DIC). Note: this image does not show the leukemia, only DIC.
- Discuss the conditions in which this can occur.
Gram-negative sepsis with endotoxemia, disasters that release tissue thromboblastic substances (obstetric complications such as abruptio placenta, major trauma, malignancies), and promyelocytic leukemia.
- Which of the following tests would be most useful to diagnose this condition in this patient with acute promyelocytic leukemia:
- A. Hemoglobin electrophoresis
- B. Reticulocyte count
- C. Coagulation tests
- D. Vitamin B12 assay
- E. Bone marrow biopsy
Answer: C The D-dimer test would be the most specific.
Additional History:
- For comparison, a CBC from a patient with maternal HELLP syndrome is shown. Spot the key feature in the RBC histogram.
There is hemolysis, so the RDW (red cell distribution width) is markedly increased, as illustrated by the RBC histogram, with a large tail to the left. HELLP is in the spectrum of toxemia of pregnancy, and is marked by hemolysis, hepatic enzyme elevation, and low platelets (thrombocytopenia). Hemolysis, particularly a microangiopathic hemolytic anemia in which the RBCs are being damaged, will lead to great variation in red cell size and shape.
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