The Translocation t(8;16)(p11;p13) Defines an AML Subtype with Distinct Cytology and Clinical Features

Abstract

Twenty-five patients with AML and t(8;16)(p11;p13) and 3 patients with identical cytological and clinical features and variant translocations involving breakpoint 8p11 have been previously reported (frequency 0.4% of AML). We describe a further case of t(8;16) and review the salient features of this form of AML. Blast morphology was monocytoid but with heavy azurophilic granulation and prominent erythrophagocytosis. Non specific esterase (NSE) positivity inhibited by sodium fluoride confirms monocytic differentiation but strong peroxidase activity and dual positivity for chloroacetate esterase and NSE suggest the involvement of a common monocytic-granulocytic precursor. The prognosis appears to be worse than in typical AML M5 and CNS disease may be a particular feature at diagnosis. There are only 5 reported survivors: 3 had allogeneic bone marrow transplants. Our patient remains in remission 2 years after autologous bone marrow transplant. Breakpoint 8p11 appears to be a critical region where PLAT, the gene for tissue plasminogen activator maps. PLAT may be the key to the pathogenesis of the coagulation defect documented in one third of cases which can be due to DIC or primary fibrinolysis. The translocation t(8;16) or its variants appear to define a distinct variant of AML, M5 with erythrophagocytosis, which does not easily fit into the FAB classification.