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Amyloidosis

Author: Vanessa Ngan, Staff Writer, 2003.

What is amyloidosis?

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.

Types of amyloidosis

There are three major types of amyloidosis.

Primary 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.

Clinical features of primary amyloidosis

Distinctive clinical features are found for each type of primary amyloidosis.

Systemic 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.

Lichen amyloidosis

Macular amyloidosis

Nodular primary localised cutaneous amyloidosis

Amyloidosis cutis dyschromicum

Amyloidosis cutis dyschromica is a newly described form of primary cutaneous amyloidosis  that causes localised hyperpigmentation and hypopigmentation.

How is the diagnosis of amyloidosis made?

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.

What is the treatment of systemic amyloidosis?

Nonspecific treatment

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.

Specific treatment

Prognosis

Most untreated patients die within 1–2 years of diagnosis of primary systemic amyloidosis from heart and/or kidney failure.

What is the treatment of primary cutaneous amyloidosis?

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 tried include topical dimethyl sulfoxide (DMSO) and phototherapy (UVB) or PUVA).

Surgical treatment to remove amyloid deposits includes laser vaporization, dermabrasion, and excision of individual lesions.  

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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