[Castleman tumor, lichen ruber and pemphigus vulgaris: paraneoplastic association of immunological diseases?].

In a 45-year-old patient with an unusual clinical course of wide-spread cutaneous and oral lichen planus as well as pemphigus vulgaris of the oral cavity, both refractory to standard therapy, a Castleman tumour was suspected. Computer tomography disclosed a solid retroperitoneal tumour in the pelvis. After its surgical removal both dermatoses regressed substantially within a matter of weeks. In 1954 and again in 1956, Castleman described a thymoma-like lymph node hyperplasia, for which various synonyms are used. Castleman tumours are classified into the common hyalin-vascular type (80-90%), the rarer plasma cell type (10-20%) and the intermediate type. It is usually a benign lymphoma of variable location, but mostly intrathoracic. There is a remarkable association of Castleman tumours with skin diseases (lichen planus, pemphigus vulgaris, Kaposi sarcoma), neurological diseases (POEMS syndrome, myasthenia gravis, arteritis temporalis, Guillain-Barré syndrome), and internal diseases (nephrotic syndrome, amyloidosis, plasmacytoma, rheumatoid arthritis, thrombotic thrombocytopenic purpura). The coincidence of Castleman tumours with various immune phenomena and immunological diseases is higher than could be expected by chance, presenting a challenging pathophysiological model of antibodies and variable immunodeficiencies.