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.