Diagnosing disseminated intravascular coagulopathy in acute promyelocytic leukemia.

Disseminated intravascular coagulopathy (DIC) (see Figure 1) is a complex, life-threatening condition that causes a hypercoagulative state, resulting in inappropriate activation of the coagulation cascade (see Figure 2). Activation of the coagulation cascade is triggered by the release of tissue factor (TF), a transmembrane glycoprotein (McCance & Huether, 2006). On release of TF, the coagulation cascade is initiated, causing an excess of thrombin to be released. With the unregulated release of thrombin, plasminogen is converted to plasmin, resulting in fibrinolysis. Fibrinolysis causes an excess of fibrin degradation products (FDPs), which initiates excessive bleeding (Holmes-Gobel, 2002), leading to a condition of simultaneous hemorrhages and clot formation. In acute promyelocytic leukemia (APL), TF is secreted directly into the bloodstream by the membranes of the promyelocyte blast cells, which initiates the coagulation cascade causing DIC (McCance & Huether). An estimated 85% of patients diagnosed with APL will develop DIC (Ezzone, 2000; Holmes-Gobel, 2000). Although DIC is common in APL, APL itself is a rare form of acute myelogenous leukemia (AML), subtype M3. APL accounts for approximately 10%–15% of adult patients diagnosed with AML (National Cancer Institute, 1999). Cytogenetically, APL is identified by a translocation between chromosomes 15 and 17 (t[15, 17]), which results in the formation of promyelocytic leukemia gene and retinoic acid receptor a (Wang & Chen, 2008).