DIC is seen most commonly seen in which ANIL type?
**Core Concept**
Acute promyelocytic leukemia (APL), also known as M3 according to the French-American-British (FAB) classification, is a subtype of acute myeloid leukemia (AML) characterized by the accumulation of immature granulocytes, particularly promyelocytes. This condition is known for its high risk of disseminated intravascular coagulation (DIC) due to the release of procoagulant substances from the abnormal cells.
**Why the Correct Answer is Right**
M3 APL is associated with a high risk of DIC due to the release of tissue factor (TF) from the promyelocytes. TF is a potent initiator of the coagulation cascade, leading to the formation of thrombi and subsequent activation of fibrinolysis, resulting in microangiopathic hemolytic anemia and thrombocytopenia. The release of other procoagulant substances, such as fibronectin and von Willebrand factor, also contributes to the development of DIC in M3 APL.
**Why Each Wrong Option is Incorrect**
**Option A:** M2 AML is characterized by the accumulation of myeloblasts with maturation, but it is not typically associated with a high risk of DIC.
**Option C:** M4 AML, also known as acute myelomonocytic leukemia, is characterized by the accumulation of myeloblasts with monocytic differentiation. While it can be associated with DIC, it is not as strongly associated as M3 APL.
**Option D:** M5 AML, also known as acute monocytic leukemia, is characterized by the accumulation of myeloblasts with monocytic differentiation. It is not typically associated with a high risk of DIC.
**Clinical Pearl / High-Yield Fact**
APL (M3) is a classic example of a leukemia that is highly responsive to all-trans retinoic acid (ATRA) therapy, which induces differentiation of the promyelocytes and reduces the risk of DIC.
**✓ Correct Answer: B. M3**