Primary cutaneous plasmacytoma: a role for a triggering stimulus?

Primary cutaneous plasmacytoma is a rare type of cutaneous B-cell lymphoma, characterized by clonal proliferation of plasma cells, that primarily develops in the skin. Five cases have been described to date in which a local triggering stimulus may be involved in development of this skin tumour. We describe the case of a primary cutaneous plasmacytoma localized to the lower lip. This site had been affected for 15 years with recurrent herpes simplex virus-1 infection. Neoplastic plasma cells were found to be bcl-2-positive. We hypothesize that chronic stimulation of keratinocytes by herpes simplex virus-1, possibly through toll-like receptors, may have favoured the release of cytokines (e.g. interleukin-6) able to induce plasma cell proliferation, transformation and survival.