In pemphigus foliaceus (PF), immunoglobulin G (IgG) autoantibodies directed against desmoglein-1 (Dsg-1), a cell adhesion molecule expressed mainly in the granular layer of the epidermis, are responsible for the intercellular widening between desmosomes resulting in intraepidermal blisters. Rituximab is a chimeric monoclonal antibody that by binding specifically to the transmembrane antigen CD20 found on the surface of normal and malignant B cells, leads to B-cell depletion. We report a 19-year-old Filipino woman with PF and controlled idiopathic thrombocytopenia purpura, initially treated with high-dose prednisone and azathioprine. Due to rapid PF progression with associated moderate reactive depression, rituximab was added to the treatment regimen with prompt improvement of lesions and clearance after five months. Five years later, lesions recurred with erythematous, dry, scaly plaques on both breasts, axillae, and on the scalp, associated with moderate to severe intermittent pruritus. After the first of a series of four weekly infusions, rituximab monotherapy resulted in immediate and sustained clearance up to 22 months. In parallel with skin clearance, serum CD19 and CD20 B cells decreased to almost zero after the first infusion, to zero after the second, while the decrease of Dsg-1 levels was more gradual, and down to normal after four months.
We offer this case report to show that rituximab can be given as a first-line monotherapy option for indications similar to ours such as drug reactions (steroid-induced depression) or a history of recalcitrant PF to the usual medications; and to suggest using CD19 and CD20 in addition to the desmoglein levels to monitor disease activity and molecular change from which to learn how to continue to monitor for disease activity after clearance.