Lymphomatoid papulosis with a natural killer-cell phenotype

Lymphomatoid papulosis (LyP) is defined as a recurrent self-healing papulon odular eruption with the histological features of a (CD30+) cutaneous T-cel l lymphoma. The atypical cells usually have a CD3+/-, CD4+/-, CD8-, CD30+, CD56- T-cell phenotype. We report an unusual case of LyP, in which the atyp ical cells expressed a CD3-, CD4-, CD8-, CD30+, CD56+ phenotype. Detailed p henotypic and genotypic analysis confirmed that these cells had a natural k iller (NK)-cell phenotype. Lymphomas with an NK-cell phenotype usually have a poor prognosis. However, the waxing and waning of papular lesions for mo re than 20 years and the excellent response to low-dose oral methotrexate i n this patient suggest similar clinical behaviour to LyP cases with a T-cel l phenotype.