Nasal and nasal-type T/NK-cell lymphoma with cutaneous involvement

Natural killer (NK) cells are a third lymphocyte lineage, in addition to B- and T-cells, that mediate cytotoxicity without prior sensitization. NK cel ls also have phenotypic and genotypic characteristics; they express the NK- related antigen CD56 and T-cell markers such as CD2 and CD3 epsilon, but th eir T-cell receptor (TCR) locus is not rearranged. Non-Hodgkin's lymphomas are divided into B- and T-cell neoplasms and NK-cell lymphomas. We describe 2 Japanese patients with nasal and nasal-type T/NK-cell lymphoma in which the skin, nasal/nasopharyngeal region, bone marrow, and lymph node were the sites of involvement. The clinical and histopathologic findings were recor ded. In addition, immunophenotyping, TCR gene rearrangement, and the existe nce of Epstein-Barr virus (EBV) DNA by polymerase chain reaction amplificat ion were determined. Clinically, the cutaneous eruptions were purplish, har d, multiple nodules, Histologically, angiocentric proliferation of small-to medium-sized, pleomorphic, lymphoid cells were observed. They revealed han d-mirror-shaped lymphocytes with azurophilic granules with the use of Giems a staining by touch smear. These lymphocytes were found to be positive to i mmunophenotyping for CD2 (Leu5b), CD3 epsilon (DAKO), CD4 (Leu3a), and CD56 (Leu 19). No clonal rearrangement of TCR-beta, -gamma and -delta genes and immunoglobulin gene markers were found, and no positive results of identif ication of EBV DNA were shown. The patients underwent cyclophosphamide, dox orubicin, vincristine, and prednisone chemotherapy with complete remission; however, both had recurrence of disease. Because NK-cell lymphomas express some T-cell markers, they may be mistakenly diagnosed as peripheral T-cell lymphomas if they are not investigated for the NK-cell-specific marker, CD 56. Therefore the importance of immunophenotypic investigations of CD56 sho uld be stressed. Also, the importance of clinical investigation of nasal/na sopharyngeal lymphomas should be stressed when NK-cell lymphoma is diagnose d involving the skin, because NK-cell lymphomas are often association ed wi th the nasal and nasopharyngeal region.