OBJECTIVETo investigate the clinicopathologic features, immunophenotype and prognosis of lymphomatoid papulosis (LyP).

METHODSClinicopathologic analysis, immunohistochemical staining (LSAB and EliVision method) and in situ hybridization for EBER were undertaken in this study.

RESULTSThirteen cases of LyP were studied, derived from six male and seven female patients with a median age of 26.4 years. The most common presentation was multiple symptomless papules or nodules, involving predominately the extremities and trunks. Histologically, the tumor primarily involved the dermis and subcutaneous layer. Six tumors were type A, one was type B and six were type C. The main infiltration patterns were wedge-shaped, band-like, sheet-like or nodular. There was epidermotropism in eight cases. Immunohistochemical staining showed that the large tumor cells in all 12 types A and C cases expressed CD30. All 13 cases expressed two to three T-cell associated antigens (CD3, CD5 or CD45RO) and one to three cytotoxic granule associated antigens (TIA-1, GrB or Perforin). All cases expressed CD4, four expressed CD8, and one expressed CD15. Only one case expressed CD20; and all cases were negative for ALK-1. The tumor cells showing epidermotropism had CD3(+), CD4(+) and CD8(-) phenotype in most cases. Only one case was EBER1/2 positive. Follow up information was available in 12 patients; all were alive at the end of the follow up period.

CONCLUSIONSLyP has distinctive clinicopathologic features and immunophenotype with favorable prognosis. In types A and C, the atypical cells showing epidermotropism were similar to those in MF, these cells possess cerebriform and hyperchromatic nuclei. The epidermotropic tumor cells and the CD30(+) large cells may be derived from different clones. EB virus may not be correlated with LyP.