Acute promyelocytic leukemia is a distinct subset of acute myelocytic leukemia with unique clinicopathologic characteristics including longer duration of relapse free survival: experience in 13 cases.

Acute promyelocytic leukemia(APL) is a subtype of acute myelocytic leukemia(AML) associated with unique features such as the presence of atypical promyelocytes and bleeding tendency due to disseminated intravascular coagulation(DIC). In a retrospective study, we analyzed 96 cases of AML seen at our hospital between June, 1989 and December 1993. Thirteen cases of APL(14%) were identified and their clinicopathologic characteristics were analyzed. The 86 cases of other types of AML served as controls. The distinct clinicopathologic features of APL as contrasted to other types of AML included younger age of patients, shorter duration of symptom before diagnosis, higher level of albumin at presentation, and a higher proportion of patients having coagulation abnormalities (75 vs. 25%). Bone marrow cellularity was higher in APL when compared to other types of AML (100 vs. 90%, P = 0.013). Of 13 patients with APL, 4 died of bleeding/sepsis between days 2 to 4 after admission. Seven of 9 patients who received induction therapy achieved complete remission(CR). CR rate in APL was similar to other types of AML (78 vs. 64%, P = 0.743). Five of seven patients who achieved CR remain in continuous CR at 9+ to 42+ months. CR duration is significantly longer in APL when compared to other types of AML (P = 0.029). In conclusion, this study showed that APL is a distinct entity among subtypes of AML with clinically significant bleeding tendency and rapidly fatal course if untreated. With appropriate antileukemic therapy, CR can be achieved in the majority of patients and the patients show a longer duration of CR when compared to other types of AML.