The Morphologic Spectrum of Cutaneous B-Cell Lymphomas

IN THE PAST, studies on malignant lymphoproliferative disorders of the skin usually concerned lymphomas of the T-cell type. As new knowledge became available through the synthesis of classic morphologic studies and progress in immunology and molecular biology, it was recognized that cutaneous B-cell lymphomas (CBCL) represent a distinct and important group of extranodal lymphomas. They occur far more frequently than generally believed and have been considerably underestimated. It has also become clear that many lymphoid proliferations previously classified as cutaneous B-cell pseudolymphomas are actually examples of CBCL with favorable clinical behaviors. Patients with CBCL can be divided into 2 groups: (1) Those withprimary cutaneous B-cell lymphomashave cutaneous disease alone with no evidence of extracutaneous manifestations over a period of at least 6 months when a complete staging examination has been performed. (2) Patients withsecondary cutaneous B-cell lymphomasshow extracutaneous disease and subsequent development of skin lesions. Secondary cutaneous B-cell lymphomas show