Laryngeal amyloidosis

by Jason Wasserman MD PhD FRCPC
August 23, 2024

Background:

Laryngeal amyloidosis is a rare condition in which an abnormal protein called amyloid builds up in the tissues of the larynx. This buildup can cause thickening and stiffness of the affected tissues, affecting the voice and breathing. Although amyloidosis can occur in other parts of the body, in laryngeal amyloidosis, the amyloid deposits are confined to the larynx.

What parts of the larynx are commonly involved in laryngeal amyloidosis?

In laryngeal amyloidosis, the most commonly involved parts of the larynx include the true vocal cords, the false vocal cords, and the subglottis (the area below the vocal cords). These areas are important for voice production and airway function, so this condition often causes hoarseness and breathing difficulties.

What are the symptoms of laryngeal amyloidosis?

The symptoms of laryngeal amyloidosis vary depending on the extent and location of the amyloid deposits.

Common symptoms include:

• Hoarseness or changes in the voice
• Difficulty breathing
• A feeling of something being stuck in the throat
• Persistent cough
• Sore throat

In some cases, the condition may be detected during a routine exam, even if no symptoms are present.

What causes laryngeal amyloidosis?

Laryngeal amyloidosis occurs when amyloid proteins accumulate in the larynx. These proteins are misfolded, meaning they do not function properly and instead form deposits in tissues. The cause of this abnormal protein buildup is not always known, but in most cases, the amyloid is made up of immunoglobulin light chains, which are proteins produced by plasma cells.

What other conditions may be associated with laryngeal amyloidosis?

Laryngeal amyloidosis can occur on its own (localized amyloidosis) or in association with a systemic condition called systemic amyloidosis, in which amyloid deposits form in multiple organs throughout the body. In rare cases, it may also be associated with a blood disorder called multiple myeloma, which affects the plasma cells (a type of immune cell) that produce immunoglobulins.

What are the microscopic features of laryngeal amyloidosis?

Under the microscope, laryngeal amyloidosis appears as pink, amorphous deposits in the tissues of the larynx. Special stains, such as Congo red, are used to confirm the presence of amyloid. When viewed under a polarized light microscope, Congo red-stained amyloid shows an apple-green birefringence (a characteristic color pattern), which is a hallmark of amyloid deposits.

What types of tests may be performed to confirm the diagnosis?

To confirm the diagnosis of laryngeal amyloidosis, a biopsy is typically performed, where a small sample of tissue from the larynx is removed and examined under a microscope. In addition to standard histological stains, special stains like Congo red are used to detect amyloid. Other tests, such as immunohistochemistry, may be done to determine the type of amyloid protein present. If systemic amyloidosis is suspected, blood and urine tests, as well as imaging studies, may be recommended to check for amyloid deposits in other parts of the body.