Amyloidosis is a rare disorder of immune complex deposition in tissues. The larynx is the most common site in the head and neck, although it really can affect any tissues in the body.
On biopsy the tissue often appears grossly as a firm tan yellow protein. On light microscopy it stains a characteristic Salmon Pink with Congo Red. Under polarized light it becomes a Birefringent Apple Green and with the addition of Potassium Permanganate you get a reversibility of the Birefringence.
Local excision as possible is therapeutic. Supportive chemotherapeutics or radiation can be palliative but do not add to survival.