CD30+ Cutaneous Lymphoproliferative Disorders and Pseudolymphomas

Abstract

CD30+ cutaneous lymphoproliferative diseases (CD30CLPD) comprise a spectrum ranging from clinically benign lymphomatoid papulosis (LyP) to primary cutaneous anaplastic large cell lymphomas (ALCL). Between ends of the spectrum are borderline cases not readily assigned to LyP or ALCL. Overall survival and disease-related survival for these disorders are excellent. However, LyP patients have a risk of developing a malignant lymphoma (usually mycosis fungoides, ALCL, or Hodgkin lymphoma). LyP and associated T-cell lymphomas are often clonally related. Fortunately, the risk of LyP patients developing a fatal extracutaneous lymphoma is less than 5 %. LyP patients also are at increased risk of developing a nonlymphoid malignancy. LyP lesions vary greatly in histology according to the age of the lesion. Five different histologic types are described. All but type B feature CD30+ cells. Skin conditions containing CD30+ cells must be distinguished from LyP. LyP resembles pityriasis lichenoides clinically but can be distinguished by combined histopathologic and immunohistochemical features. Primary cutaneous ALCL can be distinguished from secondary skin lesions of systemic ALCL by expression of CLA and lack of EMA and ALK.