The spectrum of CD30+ T cell lymphoproliferative disorders in the skin
Primary cutaneous CD30+ T cell lymphoproliferative disorders (pcCD30+ T cell LPDs) are a spectrum of pre-malignant to frankly neoplastic lymphoproliferations that comprise lymphomatoid papulosis (LyP), primary cutaneous anaplastic large cell lymphoma (pcALCL), and borderline lesions. Although the atypical T cells that are the hallmark of these disorders share the expression of CD30, as the identifying marker, the clinical presentation, histological features and clinical course are vastly different. Furthermore, histopathologic features of pcCD30+ T cell LPDs may overlap with other cutaneous and systemic lymphomas. While most pcCD30+ T cell LPDs have an excellent prognosis, systemic lymphomas typically have a poorer outcome. CD30 has now been shown to be a reliable therapeutic target in pcCD30+ T cell LPDs. This review will emphasize the structure and function of CD30, along with the clinical and pathological spectrum of pcCD30+ T cell LPDs. It will also highlight other CD30+ lymphoproliferations that must be differentiated by careful clinical and pathological correlation.