(am″ĭ-loy″dō′sĭs)

[amyloid + -osis]
Any of a group of imperfectly understood metabolic disorders resulting from the insidious deposition of amyloid fibrils in tissues. Amyloidosis may cause localized or widespread organ failure. Amyloid may infiltrate many organs, including the heart and blood vessels, brain and peripheral nerves, kidneys, liver, spleen, skin, endocrine glands, or intestines. As a result, the clinical manifestations of amyloidosis are varied, and the disease may mimic other conditions ranging from nephrotic syndrome to dementias or congestive heart failure. Amyloidosis of the tongue may cause it to become markedly enlarged, interfering with speech or swallowing. Amyloid infiltration of endocrine organs can cause pituitary, thyroid, or pancreatic dysfunction.
Primary amyloidosis is present when amyloid proteins are deposited throughout the body because of their overproduction by malignant clones of immune cells. Multiple myeloma and B-cell lymphoma are the two hematological malignancies associated with primary amyloidosis.

Secondary amyloidosis is the production and deposition of amyloid in patients with chronic inflammatory conditions, e.g., rheumatoid arthritis. This is also known as reactive, systemic amyloidosis.

Localized amyloidosis is present when amyloid infiltrates an isolated organ (such as the pancreas).

DIAGNOSIS
Amyloid in tissues can be demonstrated by its characteristically green appearance when stained with Congo red stain and viewed under a polarizing microscope.

TREATMENT
Corticosteroids and melphalan or very high-dose chemotherapy followed by stem-cell transplantation has been used to treat primary amyloidosis. In secondary amyloidosis, controlling the primary inflammatory illness may arrest the progress of the disease.

AA amyloidosis

Amyloidosis in which amyloid A protein, a protein manufactured by the liver in chronic inflammatory diseases, deposits in tissues and causes organ dysfunction.

AL amyloidosis

Amyloidosis in which immunoglobulin light chains (or parts of light chains) circulate in serum and deposit in tissues such as the kidneys. They may cause significant organ dysfunction; e.g., in the kidneys they can cause nephrotic-range proteinuria and end-stage disease.

dialysis-related amyloidosis

ABBR: DRA. The accumulation of beta-2-microalbumin, a type of albumin, in the blood of patients undergoing hemodialysis. The molecule is not readily removed from the blood by some dialysis membranes, and, when the protein builds up in joints and bones, it can cause pain and loss of function, esp. at the wrist, where it produces carpal tunnel syndrome.

familial amyloidosis

The only inherited form of amyloidosis. In this variant of the disease, transthyretin is manufactured by the liver and deposits in a wide variety of tissues, causing them to malfunction.

lichen amyloidosis

Amyloidosis limited to the skin.

localized amyloidosis

Amyloidosis in which isolated amyloid tumors are formed.

primary amyloidosis

Amyloidosis not associated with a chronic disease.

secondary amyloidosis

Amyloidosis associated with a chronic disease, e.g., tuberculosis, syphilis, or Hodgkin disease, and with extensive tissue destruction. The spleen, liver, kidneys, and adrenal cortex are most frequently involved.