Castleman's disease associated pemphigus. A form of paraneoplastic pemphigus

We report a patient with Castleman's disease (angio-follicular lymph node hyperplasia) associated with a pemphigus vulgaris-like disorder. The patient had the hyaline-vascular mediastinal type of Castleman's disease and developed painful oral erosions and penile lesions. Histologic examination revealed an interface dermatitis including vacuolar changes, necrotic keratinocytes and a lichenoid infiltrate. In addition there was suprabasal vesiculation with acantholysis, reminiscent of pemphigus vulgaris. Direct immunoperoxidase staining for intercellular IgG was positive. HLA typing revealed that the patient did not have an HLA haplotype known to be associated with susceptibility to pemphigus. Until now, Castleman's disease Associated Pemphigus (CDAP) has been regarded as a unique entity presenting as atypical pemphigus vulgaris. However, a review of the literature reveals that the clinical and histologic signs of CDAP are virtually identical to those of paraneoplastic pemphigus and that both entities are associated with a lymphoproliferative disorder. We suggest that CDAP is a form of paraneoplastic pemphigus.