Extraosseus plasmacytoma of the pharynx with localized light chain deposition. Case report

Light chain deposition disease (LCDD) is a rare disorder associated with a clonal proliferation of plasma cells, which synthesize abnormal monoclonal immunoglobulin light chains. It is characterized by systemic deposition of light chains in various organs, with the kidneys being most commonly affected. There have been few reports of isolated LCDD, i.e. in the brain, lungs and cervical lymph nodes. We here report on another patient with an isolated form of LCDD, which was limited to the pharyngeal mucosa and was associated with an extraosseus plasmacytoma of the pharynx, expanding the spectrum that has been recognized for LCDD. The patient was treated by local radiotherapy, with an excellent response. A less aggressive clinical course can probably be expected than in the usual form of LCDD, but a long-term follow-up is necessary to establish the clinical significance of this variant of LCDD.