Large atypical cells of lymphomatoid papulosis are CD56-negative: a study of 18 cases.

Background: Histologically, diffuse dermal infiltrates of large atypical lymphocytes can be seen in lesions as indolent as type C lymphomatoid papulosis (LyP) to ones as aggressive as NK/T-cell lymphoma. While lesions of lymphomatoid papulosis are definitionally positive for CD30, their ability to express CD56 has not been formally studied. The objective of the current study was to determine whether or not the large atypical cells of LyP express the natural killer cell marker, CD56.

Methods: Biopsies from 18 patients with LyP were studied with monoclonal antibodies to CD30, CD56, CD8, and TIA-1. These included four type C LyP lesions. Clinical information was obtained by chart review and included extent of LyP lesions, presence/absence of disease at follow-up, and any associated hematologic malignancies,.

Results: None of the biopsies exhibited CD56 positivity within the large atypical cells of LyP. While some biopsies demonstrated CD56-positive, small, presumably reactive, lymphocytes within the infiltrate, their presence did not correlate with extent of disease, persistence of disease, or propensity for an associated non-LyP hematologic malignancy.

Conclusions: The large atypical cells of types A and C LyP do not exhibit positivity for CD56, and thus a panel of antibodies that includes CD30 and CD56 can readily distinguish between the benign end of the spectrum of CD30-positive lymphoproliferations and aggressive NK/T-cell lymphoma.