Amyloidosis

Amyloidosis is deposition of fibrillar proteins in the extracellular matrix.  It can occur as solitary or systemic amyloidosis.  The deposition is characterized by acellular, amorphous, and eosinophilic material.  Scattered chronic inflammatory infiltrates are also visible.

Nonbranching fibrillar structures can be identified with electron microscopy as shown here.

Amyloidosis arises when fibrils alter its secondary protein structure such that it becomes insoluble in the tissue. The deposition of insoluble protein fibrils leads to organ dysfunction. The etiology is unclear, but genetics play important roles. There are well over 20 different types of human amyloidosis. In the head and neck region, amyloidosis commonly occurs as a solitary lesion. The two most common sites of amyloidosis are the larynx and tongue. With laryngeal amyloidosis, patients typically present with dysphonia. Differential diagnosis includes vocal nodules or polyps and lipoid proteinosis. Nasopharyngoscopy with resection of the lesion should be performed for both diagnosis and treatment. The specimen should undergo Congo-Red staining as well as immunocytochemistry to determine the specific amyloid fibril precursor, which will assist in identifying any underlying etiologic factors, and the subsequent management of the disorder.