Amyloidosis is the name given to a group of rare, complicated disorders in which amyloid consisting of misfolded proteins, which are relatively insoluble, deposit and accumulate, in no particular order, in tissues and organs of the body with the exception of the brain. As these deposits progressively build up they impair the working of the organs which without treatment eventually leads to organ failure
The main types of amyloidosis, AL, ATTR, AA are referred to as systemic diseases because the amyloid can deposit in any organ of the body. Also the production of the amyloid forming protein, the precursor protein, is distant to the organs in which the amyloid forming protein is depositing.
This is different in localised amyloidosis where the amyloid-forming protein is produced and deposited in the same part of the body.
Localised amyloidosis is also known as Localised light chain amyloidosis. Why? AL (light chain) amyloidosis is caused by an abnormal protein (the light chain of an immunoglobulin or antibody protein) made by abnormal plasma cells found in the bone marrow.
Abnormal plasma cells producing light chains are usually found in the affected tissues of patients with localised amyloidosis, however it is rarely associated with detection of a serum monoclonal protein in blood tests and has a normal free light chain ratio.
Localised amyloidosis of a non-AL type may very rarely be found incidentally in areas such as glandular tissues and blood vessels. This generally does not require treatment or follow up.
Localised AL amyloidosis is an:
- Acquired disease and is not inherited.
- The amyloid deposits are both produced and deposited in one isolated part of the body.
- The prognosis of localized amyloidosis is excellent. A study of 606 patients diagnosed with localised amyloidosis at the National Amyloidosis Centre between 1980 and 2011 concluded that only one patient progressed to systemic amyloidosis.
Parts of the body most commonly affected by localised amyloidosis?
Especially the conjunctiva (If deposits are symptomatic they may have to be excised).
Often presents as small pseudo tumors localized in the renal pelvis, ureters and bladder.
May present as what is called macular (flat) lesion or popular (raised) lesion. This is sometimes known as lichen amyloidosis which is often seen in the skin on thighs and forearms. Most often seen in people with a dark skin.
Upper airways and lungs
May also be seen in the respiratory system throat and lung tissue.
Gastro intestinal tract
Deposits may be found in the stomach or intestine.
Insulin injection sites
Occasionally localised amyloidosis is found in the skin around the injection sites of insulin dependent diabetics.
In localised amyloidosis deposits often appear as small nodules or tumors and may be treated by local incision. This may cure the disease however the amyloid may recur in the future in the same area of the body and need further excision, laser surgery or other localized treatment.
Symptoms may be vague and sometimes nonexistent. They will vary according to where the amyloid occurs. Localised amyloidosis may be found incidentally when procedures such as endoscopy or cystoscopy are being carried out.
- Eye. Local deposits may affect the cornea affecting sight.
- Genitourinary tract. Bladder irritation. Burning sensation on passing urine. Passing blood.
- Skin. An Itch, raised annoying nodules on the skin.
- Upper airways. Shortness of breath, cough, hoarseness.
- Gastrointestinal Tract. Heart burn, constipation, bleeding in the gut
- Amyloidosis can only be definitively diagnosed through a tissue or organ biopsy.
- In localized amyloidosis a tissue biopsy will involve taking a small piece of the tissue from the affected area.
- The biopsy is then stained with a dye, Congo red, in the laboratory.
- If amyloid is present, the biopsy will appear red under normal light and green (apple-green birefringence) under special polarized light
2nd procedure in the laboratory
- Further testing on the biopsy to identify the type of amyloidosis by identifying the protein composition of the amyloid fibrils.
- It is imperative to identify the “type” even though all information may point to the diagnosis being localized amyloidosis, as treatment is different for each type of amyloid.
To be certain that this is localized disease the usual work up tests will be performed to rule out systemic amyloidosis.
These may include:
- A bone marrow biopsy
- Free light chain tests
- Urine tests
Once the diagnosis has been established patients may undergo further tests and have consultations with other specialists to establish the extent of the amyloid deposition in the one area and form a treatment plan.
Chemotherapy has no place in the treatment of Localised amyloidosis.
- No treatment may be needed.
- Symptomatic treatment including surgical excision or laser surgery.
- Localised amyloidosis may be completely curable by removing the amyloid deposits by surgical excision. However, there is a chance it will grow back again into the same area.
The prognosis for localised amyloidosis is good.
Follow up will mainly by the relevant specialist treating the area affected by the amyloid protein. For example an eye surgeon, ENT specialist, respiratory physician, gastroenterologist, dermatologist or other specialists.
It is however important that patients are followed up on a regular basis by an amyloidosis clinical team to be certain that the localized disease does not become systemic.
This web site does not contain information on the most common form of localized amyloid angiopathy (CAA) which is totally unrelated to the local or systemic amyloidosis being discussed here.
Read The National Amyloidosis London’s patient information sheet on localized amyloidosis.