Lymphomatoid papulosis type A: clinical, morphologic, and immunophenotypic study.
BACKGROUND: Lymphomatoid papulosis (LyP) is a cutaneous clonal or polyclonal Ki-1 + T-cell lymphoproliferative disorder, morphologically resembling Ki-1 + anaplastic large cell lymphomas (Ki-1 + ALCL) or Hodgkin's disease (HD). Lymphomatoid papulosis usually has a characteristic benign clinical course with remissions and relapses of the cutaneous eruptions. METHODS: The authors studied three patients with LyP. In each case the diagnosis was established based on the typical clinical history and presentation of the cutaneous lesions as well as the morphologic and immunophenotypic findings. RESULTS: In all three cases the skin biopsies showed a polymorphic, nonepidermotropic, dermal lymphocytic infiltrate, composed of small lymphocytes and fewer large, atypical cells. The large cells were positive for the activation markers CD30 (Ki-1) and CD45R (leukocyte common antigen), and were negative for the HD marker CD15 (Leu MI). CONCLUSIONS: In most cases, LyP can be distinguished from Ki-1 + ALCL and HD on the basis of clinical, morphologic, and/or immunophenotypic findings. We emphasize the importance of the recognition of LyP as a clinicopathologic entity and the awareness of dermatologists, oncologists, and surgical pathologists in differentiating LyP from other primary cutaneous Ki-1 + lymphoproliferative disorders (Ki-1 + ALCL and HD). The prognosis of cutaneous Ki-1 + ALCL and HD is usually different from LyP and requires a different therapeutic approach.