This course addresses the often difficult differential diagnosis of cutaneous lymphoid infiltrates. Three main topics will be discussed: Cutaneous T cell lymphomas, B cell lymphomas, and benign lymphoid infiltrates that mimic lymphoma (pseudolymphomas). In each instance, correlation between clinical features and histopathology will be emphasized. The use of immunohistochemistry and

molecular methods to clarify the diagnosis will be illustrated and the limitations of these methods discussed. Specific entities to be presented are: 1) mycosis fungoides and its variants, 2) Sezary syndrome, 3) CD30+ cutaneous lymphomas including lymphomatoid papulosis, 4) subcutaneous panniculitis-like T cell lymphoma, 5) natural killer cell leukemia/lymphoma, 6) follicle center cell lymphoma, 7) marginal zone lymphoma (MALT), 8) immunocytoma, 9) large B cell lymphoma, 10) lichenoid reactions simulating lymphoma, 11) atypical pigmented purpuric dermatitis, 12) lymphomatoid hypersensitivity reaction to drugs, arthropod bites, and contactants, 13) figurate erythemas, 14) light reactions, 15) panniculitic disorders simulating lymphoma, 16) HIV associated reactions. A case method of presentation will be used. A limited number of loan sets of representative slides from 13 cases will be mailed in advance and transparencies will be mailed to all registrants after the meeting. A syllabus will be distributed at the time of the course. (Last Scheduled Presentation)