Amyloidosis of the head and neck: a clinicopathological study of cases with long-term follow-up

Extracellular deposits of insoluble proteinaceous material giving a starchlike reaction when treated with iodine and sulphuric acid and accumulating in tissue was for the first time described by Rokitansky in 1842 [1]. It was not until 1851 that Virchow applied the term “amyloidosis” to describe this deposition [2]. An amorphous substance called amyloid (insoluble fibril-forming protein) is deposited in extracellular spaces of organs and tissues. Amyloid deposits, under the electron microscope, appear as nonbranching fibrils with a cross-linked, β-pleated sheet conformation. They are eosinophilic after haematoxylin–eosin staining and display apple-green birefringence with polarized light when stained with Congo red. Chronic inflammations of bacterial or non-bacterial origin and immunological immune-competent neoplasm cells are examples of factors that induce amyloid fibril biosynthesis. The organs and tissues where amyloid deposits occur become stiff and plastic, having a hyaline-like appearance that leads to a loss of previous function [3]. Amyloidosis is probably caused by rearrangement in the immune system, though its pathogenesis is not still known thoroughly. It is a heterogeneous group of diseases having misfolding of extracellular protein as a common etiological factor. Chronic inflammation with extensive tissue destruction, malignant proliferation of plasmocytes and autoimmune diseases promote expansion of amyloidosis. Various clinical types of amyloidosis have an impact on its natural course, therapy and prognosis. Amyloidosis can be divided into various biochemical forms depending on amyloid deposit type: NH2-terminal immunoglobulin fragments or their light chains (AL protein); AA protein originated from serum amyloid A (SAA); transthyretin in senile amyloidosis; amino acid sequences of insulin, glutathione, calcitonin, β2microglobulin in chronic haemodialysed patients, APP protein in Alzheimer disease patients, amylin, natriuretic peptide are exemplary proteins, which can accumulate in the tissue forming amyloid [4–7]. Amyloidosis can be clinically divided into localized or systemic with extremely different clinical course. Kidneys, spleen, liver and heart, but also adrenals, pituitary gland, thyroid and alimentary tract are the organs most frequently affected by systemic amyloidosis. The most significantly involved organ systems are heart and kidneys. Extracellular deposition of amyloid leads to their failure, which constitutes the two leading causes of death of patients with systemic amyloidosis. Corresponding author: Wioletta Pietruszewska Department of Otolaryngology and Laryngological Oncology Medical University of Lodz 22 Kopcinskiego St 90-153 Lodz, Poland Phone: +48 602 225 721 E-mail: wioletta.pietruszewska @umed.lodz.pl Letter to the Editor