Cutaneous lymphoblastic lymphoma of putative plasmacytoid dendritic cell-precursor origin: two cases

Although the neoplasm of relatively mature type plasmacytoid dendritic cells (pDC) was recently reported, that of pDC-precursor has not yet been defined. We experienced two elderly male Japanese patients with reddish skin tumors. The histology of the tumors in both patients showed terminal deoxinucleotidyl transferase (TdT)-positive lymphoblastic lymphoma (LBL). The pathological cells did not express T, B or NK markers, and no rearranged bands were shown for immunoglobulin (Ig)-JH, T cell receptor (TCR)-Cβ, Jγ, Jδ1, and c-myc. In addition, no Epstein-Barr virus (EBV)-derived DNA was detected in either case. The cells were (CD45, CD43, CD74, CD10, and HLA-DR)-positive in both cases, and one of the cases showed (CD4, CD36, CD54, CD58 and CD86)-positive plasmacytoid lymphoblasts, which appeared to be compatible with intermediate cells between human bone marrow lymphoid precursors and mature lymphoid DC. The cutaneous LBL in the two cases may, therefore, have been of pDC-precursor origin.