Localised laryngotracheal amyloidosis: a differential diagnosis not to forget

Abstract

We present a case of multifocal laryngotracheal amyloidosis (LTA) in a 43-year-old man with persistent and progressive dysphonia and dyspnoea, and a first inconclusive histology. Although laryngeal amyloidosis accounts for fewer than 1% of all benign laryngeal tumours, it is in fact the most common site of amyloid deposition in the head, neck and respiratory tract. The clinical scenario is non-specific and diagnosis depends on a high degree of suspicion and on histology. Imaging is useful in mapping lesions, which are often more extensive than they appear during laryngoscopy. Despite being a benign entity, the prognosis is variable with a high-rate and long-latency recurrences, requiring long-term follow-up.

Keywords: ear; nose and throat/otolaryngology; otolaryngology / ENT; pathology; radiology.

Figure 1

Static images from the videolaryngoscopy (A, B) show a large exophytic and lobulated yellowish mass at the supraglottis filling most of the supraglottic airway, precluding the visualisation of the vocal cords.

Figure 2

Contrast-enhanced CT of the neck: (A–D) axial images through the larynx, (E–H) axial images through the trachea, (I) coronal and (J) sagittal images, demonstrate a nodular, vegetating soft tissue mass at the level of the epiglottis petiole and pre-epiglottic space (arrows in B and C), involving the right aryepiglottic fold (arrow in A) and extending down to the level of the anterior commissure (arrow in D). The lesion protrudes into the airway reducing the lumen of the laryngeal vestibule and glottis. It is homogeneous and isodense to muscle on these contrast-enhanced images. The laryngeal cartilages are intact and there is no extralaryngeal extent. Axial section through the infraglottis shows no abnormal soft tissue thickening (E). The sections through the proximal trachea show irregular thickening of the endotracheal soft tissues investing the anterior aspect of the first tracheal rings sparing the posterior tracheal wall (F–H). Note a tiny calcification in the left lateral aspect of the tracheal lesion (arrow in H). The coronal (I) and sagittal (J) images show to advantage the craniocaudal extent of the lesions and the reduction of the laryngeal and tracheal airway.

Figure 3

Histopathology slices (medium power): (A) H&E shows a biopsy fragment covered by respiratory epithelium with an acellular amorphous eosinophilic deposit in the stroma. (B) Congo red stain demonstrates a salmon colour on bright light and apple-green birefringence under polarised light (not shown).

Figure 4

Contrast-enhanced CT scan of the neck. Axial images through the larynx (A–C), axial images through the trachea (D–F) and sagittal images (G, H) show marked decrease in the size of the supraglottic mass lesion after mechanical bronchoscopy-guided resection as well as the interval appearance of nodular soft tissue thickening of the ventricular fold (arrow in B) and right vocal cord (arrow in C) which were not seen previously. Sections through the trachea (D–F) show a saber-like tracheal deformity secondary to the prior tracheostomy as well as increased, almost circumferential, thickening of the endotracheal soft tissues consistent with persistent/recurrent disease. Compared with previously, the calibre of the laryngeal airway has increased but the lumen of the proximal trachea decreased (arrow in H), justifying the aggravation of clinical symptoms (new onset of dyspnoea).

Figure 5

Contrast-enhanced CT of the neck. Axial images through the larynx (A–C), axial images through the trachea (D–F) and sagittal images (G, H) after the bronchoscopy-guided resection show normalisation of the right vocal cord (C) with adequate lumen of the glottic and supraglottic airway although with some persistent soft tissue thickening of the epiglottic petiole and pre-epiglottic space (arrows in A and B). The images through the trachea also show a decrease in the thickness of the endotracheal soft tissues with a wider tracheal lumen compared with before. This is best appreciated on the sagittal images.