The first case of blastic plasmacytoid dendritic cell neoplasm with MLL-ENL rearrangement

Abstract

Blastic plasmacytoid dendritic cell neoplasm (BPDCN), previusly referred to as blastic NK-cell lymphoma or CD4+/CD56+ ematodermic neoplasm, is an extremely rare hematologic maligancy which is characterized by co-expression of CD4 and CD56 ithout any other lineage-specific markers [1]. The disease was ategorized as a type of NK-cell lymphoma, but is now classified as rare subgroup of acute myeloid leukemia (AML) and related preursor myeloid neoplasms in the WHO classification 4th edition, ecause the precursor of plasmacytoid dendritic cells (pDCs) were dentified as the origin of the malignancy [2]. MLL gene, located at chromosome 11 band q23, is one of the most ommon targets for translocations associated with various types of dult and pediatric acute leukemia. MLL gene rearrangements are ound in 2.8% of AML patients and are relatively common in infant cute lymphoblastic leukemia and secondary AML. AML with MLL earrangement carries a relatively worse outcome [3]. Here we report a patient with BPDCN with MLL-ENL fusion gene. o our knowledge, this is the first report of BPDCN with MLL-ENL earrangement. A 45-year-old male without remarkable medical history visted our hospital because of multiple disseminated purpuric skin odules over the trunk, the limbs, and the face. Lymphadenopahy was not noted. Laboratory examinations revealed neutropenia Neutrophils, 0.492 × 109/L) and anemia (hemoglobin concentraion, 11.2 g/dL). Histological examination of the skin lesion showed iffuse infiltration of medium to large sized agranular blastic cells nto the dermis and the subcutaneous adipose tissue (Fig. 1). Bone arrow and peripheral blood infiltration were also observed. The eoplastic cells were negative for peroxidase, and flow cytomery revealed that the neoplastic cells were positive for CD4, CD11c, D33, CD45RA, CD56, CD68, CD117, CD123, HLA-DR and negative or CD3, CD5, CD7, CD8, CD10, CD11b, CD13, CD19, CD20, CD34,