Localized amyloidosis and extramedullary plasmacytoma involving the larynx of a child.

Extramedullary plasmacytoma of the larynx and localized laryngeal amyloidosis are 2 uncommon disease entities that are exceedingly rare in children. We report a case of a 12-year-old girl presenting with progressive hoarseness who was subsequently found to have extramedullary plasmacytoma coexisting with localized amyloidosis involving the larynx. Results from the immunohistochemical and molecular studies showed that the tumor cells of the plasmacytoma were monoclonal (kappa-restricted), strongly supporting their neoplastic nature. The biochemical nature of the amyloid deposits was also shown to be of kappa immunoglobulin light chain, suggesting the pathogenetic relationship between the plasmacytoma and amyloid deposition in the larynx of this patient. There was no other evidence of malignancy or amyloidosis elsewhere. On a follow-up period of 4 years, this patient was well and asymptomatic. We believe that this represents the first case in the literature showing the coexistence of extramedullary plasmacytoma and localized amyloidosis of the larynx in children. This case also supports the concept that localized laryngeal amyloidosis may be a manifestation of low-grade B-cell neoplasms.