A case of primary cutaneous CD56+, TdT+, CD4+, blastic NK-cell lymphoma in a 19-year-old woman.

The classification of blastic or blastoid natural killer (NK)-cell lymphoma is controversial. Reports of primary cutaneous blastic CD56+ NK-cell lymphoma are rare, which necessitates further clinicopathologic definition of this type of lymphoma. Most CD56+ lymphomas display angiocentric histologic features, especially in Asian patients, and these are mostly associated with the presence of Epstein-Barr virus (EBV) genome and with an aggressive clinical course. We report on a young woman with a primary cutaneous blastic NK lymphoma which showed no angiocentric features but showed an unusual immunophenotype; CD56+, TdT+, CD4+, EBV-, and germline configuration of T-cell receptor gene. This unusual lymphoblastic lymphoma seems to have an immature or progenitor NK cell lineage.