Primary cutaneous CD30 + lymphoproliferative disorders

Lymphomatoid papulosis and cutaneous anaplastic large cell lymphoma are included in the group of the "primary cutaneous CD30+ T-cell lymphoproliferative disorders" in the 2018 update of the classification of cutaneous lymphoma. This chapter deals with primary cutaneous CD30+ lymphoproliferative disorders. Several variations are included in this disorder classification, namely, lymphomatoid papulosis, cutaneous anaplastic large cell lymphoma, intralymphatic CD30+ large T-cell lymphoma, implant-associated anaplastic large cell lymphoma, borderline cases such as regressing atypical histiocytosis and primary cutaneous Hodgkin lymphoma. The chapter focuses on clinical features, histopathology, immunophenotype, and molecular genetics, treatment, and prognosis of the lymphoproliferative disorders. CD30 is a very important marker for diagnosis and classification of cutaneous lymphomas. It has been suggested that CD30 and CD30 ligand are involved in the control of apoptosis and that activation of the CD30 signaling pathway plays a role in tumor regression.