“…As regards histopathology, the tumor cells comprise a monomorphic population of small-to middle-sized cells, with round or irregular nuclei, conspicuous chromatin, partially visible nucleoli, and scant to moderate amounts of cytoplasm with fine granules (22). As regards immunohistochemistry, the BPDCN cells may be positive for CD4, CD43, CD45RA, CD56, BDCA-2/CD303, BDCA-4/CD304, CD123, T-cell leukemia/lymphoma protein 1 (TCL1), cutaneous lymphocyte antigen, CD68, CD7, CD38, CD99, S-100, TdT and CD31, according to previous reports, and are often negative for lymphoid (CD3, CD19 and CD20) and myeloid (CD117, MPO) markers (6,(23)(24)(25)(26)(27); EBER, Ig heavy chain rearrangement and TCR rearrangement are also usually negative (12,24).…”