Rare amyloidoma of the tongue base: A case report and review of the literature

Abstract

Localized amyloidosis is a rare condition characterized by the deposition of misfolding protein in a tissue, without other systemic manifestations. Only a small number of cases of localized amyloidosis of the tongue have been reported to date, in contrast to systemic amyloidosis, in which localization on the tongue is common. This study presents a rare case of localized amyloidosis of the tongue (amyloidoma) and provides a summary of the known literature of localized amyloidosis. This study describes the case of a 36-year-old female who presented with a swelling of the tongue base. The diagnosis of amyloidoma was made based on the findings of the physical examination, head and neck MRI findings and the histopathological examination with Congo red stain under polarized light. The histopathological diagnosis was as follows: Localized lambda light-chain amyloidosis. A thorough physical examination was performed by the ENT and Hematology/Oncology departments, without revealing signs of systemic disease. A series of hematological and imaging tests were also performed to verify that there was no sign of systemic involvement. The patient declined surgical excision and the 2-year follow-up did not reveal any changes in tumor dimension. Although the etiology of localized amyloidosis is yet not clear, the prolonged reaction of tissue plasma cells to environmental antigens may be a causative factor for the initiation of the neoplastic process.

Keywords: amyloidoma; biopsy; immunohistochemistry testing; microscopic examination; rare condition; tongue.

Figure 1.

Endoscopic view showing a yellowish mass at the base of the tongue on the right side. The epiglottis is partially visible, on the left side, as well as the arytenoids.

Figure 2.

(A) MRI axial and (B) sagittal view showing a polypoid mass located on the base of the tongue, partially occupying the right vallecula. Arrows indicate the lining between tumor and normal tissue (lack of invasion).

Figure 3.

(A) Hematoxylin and eosin staining showing an eosinophilic amorphous material in the connective tissue beneath the intact epithelium (magnification, x4). (B-D) Congo red staining showing a red homogenous material (arrows) under light microscopy (magnification, x4, x10 and x40, respectively).

Figure 4.

Red homogenous subepithelial deposits (star symbols) in Congo red staining (A and B) turn into an apple-green birefringence (arrows) under polarized light [magnification, x40 (A) and x4 (B), respectively].