Paraneoplastic pemphigus associated with CD20-positive follicular non-Hodgkin's lymphoma treated with rituximab: a third case resistant to rituximab therapy.

Paraneoplastic pemphigus is an IgG-mediated disease characterized clinically by a polymorphous blistering eruption with severe mucosal involvement associated with an underlying or occult malignancy. It is associated with high mortality, and response to treatment is generally poor. Potent immunosuppression is often necessary to control progression of the disease. Three case reports have documented successful treatment of paraneoplastic pemphigus with rituximab, an anti-CD20 monoclonal antibody. However, two previous reports have noted that rituximab was unsuccessful in halting progression of PNP. We report a third case of paraneoplastic pemphigus associated with follicular non-Hodgkin's lymphoma in which rituximab was not effective. Whether rituximab is an effective and novel treatment for paraneoplastic pemphigus remains undecided.