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Author: Vanessa Ngan, Staff Writer, 2003.
Amyloidosis is the term used for a group of diseases where one or more body organs accumulate various insoluble proteins (amyloid) in amounts to cause dysfunction of the organ system. Organs often affected include the heart, kidney, gastrointestinal tract, nervous system and skin. Amyloidosis of the skin is called cutaneous amyloidosis. In this condition, amyloid or amyloid-like proteins are deposited in the dermis.
There are three important types of amyloidosis.
Types of primary localised cutaneous amyloidosis include:
Secondary systemic amyloidosis
Familial (hereditary) amyloidosis
Familial amyloidosis is a rare form of amyloidosis that is inherited and most commonly causes cardiomyopathy and neuropathy in middle age. The most common form, known as ATTR amyloidosis, is due to a mutation in the transthyretin (TTR) gene on chromosome 5 and leads to faulty hepatic transthyretin protein.
Distinctive clinical features are found for each type of primary amyloidosis.
The signs and symptoms of primary systemic amyloidosis are generally non-specific and include:
These may precede the diagnosis of amyloidosis by up to two years. However, when they present together with the following specific symptoms, systemic amyloidosis should be considered a possible diagnosis.
Amyloidosis cutis dyschromica is a newly described form of primary cutaneous amyloidosis that causes localised hyperpigmentation and hypopigmentation.
The diagnosis of the various types of primary cutaneous amyloidosis is made by its clinical appearance and by the characteristic histology changes seen on skin biopsy. See also systemic amyloidosis pathology.
Treatment is directed at maintaining the function of affected organs. For example, kidney failure can be treated with dialysis and congestive heart failure with diuretics.
Most untreated patients die within 1–2 years of diagnosis of primary systemic amyloidosis from heart or kidney failure.
The treatment of lichen and macular amyloidosis is focused on relieving itch. Sedating antihistamines can be moderately effective. Topical and intralesional steroids may provide some relief if used with other treatments. Other treatments include topical dimethyl sulfoxide (DMSO) and phototherapy (UVB or PUVA).
The main aim of treatment of nodular primary localised cutaneous amyloidosis is to improve the appearance. Several methods are used and include antibiotics, topical and intralesional corticosteroids, cryotherapy, dermabrasion, shaving, curettage and electrodesiccation, carbon dioxide laser, and pulsed dye laser.
Primary cutaneous amyloidosis tends to persist or recur after treatment, but remains confined to the skin and does not evolve to systemic disease.
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