All patients received 2 doses of 1 g of rituximab 2 weeks apart (modeled after the dosing method used in rheumatoid arthritis studies).9 No peri-infusional steroids were administered. Clinical assessments were performed at baseline, day 15, and weeks 4, 8, 12, 16, 20, 24, 36, and 48. One of us (L.C.) performed the following evaluations for all patients at each visit: physical examination, MMT, photographs, and evaluation of skin disease. Skin involvement was quantified by the DSSI, a novel instrument based on the Psoriasis Area and Severity Index, which evaluates severity (erythema, induration, and scale) and extent of cutaneous disease (C. L. Carroll, MD, and J. L. Jorizzo, MD, unpublished data, 2002-2004). Based on physician and patient global assessments, a score of less than 2 is consistent with mild disease; 2 through 6, with moderate disease; and greater than 6, with severe disease. Subjective assessments included the modified Health Assessment Questionnaire16 and 3 visual analogue scales: patient and physician global assessments and patient assessment of pruritus. Laboratory evaluations included a complete blood cell count and determination of creatinine, albumin, alanine aminotransferase, CPK, and aldolase levels. CD19+ B cells were measured at baseline, day 15, and weeks 4, 12, 24, 36, and 48. Human antichimeric antibody levels were obtained at baseline and weeks 12, 24, 36, and 48.