Localized median tongue AL amyloidosis accompanied with chondroid metaplasia: the possible etiology and relationship to median rhomboid glossitis

Abstract

In the oral cavity, amyloidosis is rare and predominantly occurs in the tongue. We report a case of extremely rare AL amyloidosis accompanied with chondroid metaplasia in the tongue. Patient was a 66-year-old man with elastic hard mass on dorsum of the tongue in the median. The tongue papillae of the surface mucosa were atrophic, and candida was detected by microbial test. Biopsy was performed, and histological specimen showed a mass lesion consisted of subepithelial deposition of amorphous eosinophilic material admixed with focal chondroid areas. The deposits were positive for Congo red staining with apple-green birefringence under polarized light. Immunohistochemically, the deposits were positive for amyloid-kappa, and chondroid lesion was positive for SOX9 antibody. Finally, we diagnosed this lesion as AL amyloidosis with chondroid metaplasia. After the histological diagnosis, systemic examination was performed. The amyloid deposition was only observed in the tongue, and there was no hematopoietic disease or other diseases that could cause systemic amyloidosis. This was the first report of localized amyloidosis of the mobile tongue accompanied with chondroid metaplasia. The etiology of this case might be associated with median rhomboid glossitis.