Paraneoplastic disorders can be broadly de¢ ned as those that are caused by a remote e¡
ect of a cancer, not by direct tumor in¢ ltration or tissue damage caused by metastases.
These remote e¡ ects can be due to secretion of biologically active peptides or, in some
cases, by immunologic e¡ ects of the tumor on the resident immune system. Paraneoplastic
pemphigus (PNP) is an example of a paraneoplastic phenomenon caused by an
autoimmune disease initiated by an underlying lymphoproliferative disorder (Anhalt et al …

Abstract Background and Methods. We describe five patients with underlying neoplasms in
whom painful mucosal ulcerations and polymorphous skin lesions developed, usually with
progression to blistering eruptions on the trunk and extremities. Histologic examination
showed vacuolization of epidermal basal cells, keratinocyte necrosis, and acantholysis.
Immunofluorescence testing revealed atypical pemphigus-like autoantibodies in perilesional
epithelium and serum from all five patients. We studied the antigenic specificities of the …