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 layer of skin.

Types of amyloidosis

There are three major types of amyloidosis:

Primary amyloidosis

This disorder of protein metabolism originates in the bone marrow and is occasionally associated with multiple myeloma. It is sometimes also referred to as amyloid L chain type (AL) amyloidosis.

Primary systemic amyloidosis affects the heart, kidneys, liver, gastrointestinal tract and central nervous system. Skin involvement occurs in about 30-40% of patients.

Amyloidosis confined to the skin is called primary localised cutaneous amyloidosis. Several different types of primary localised cutaneous amyloidosis exist. These include lichen amyloidosis, macular amyloidosis and nodular primary localised cutaneous amyloidosis.

Secondary systemic amyloidosis

This occurs as a complication of many chronic inflammatory diseases such as rheumatoid arthritis and osteomyelitis.

It is also known as amyloid A (AA) amyloidosis and is the most common form of systemic amyloidosis worldwide.

The kidney, liver and spleen are the organs are most affected in secondary systemic amyloidosis. Skin involvement is rarely a feature of the disease.

Familial (hereditary) amyloidosis

This is a rare form of amyloidosis that is inherited and most commonly affects the kidneys. It is due to a mutated gene on chromosome 5.

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 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

How is the diagnosis 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?

There is no specific treatment for primary systemic amyloidosis. 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. Some treatments that have been tried with limited success include chemotherapy with melphalan and prednisone, and colchicine to inhibit amyloid deposition. Bone marrow ablation and transplantation is an experimental therapy. Most patients die within 1-2 years of diagnosis of primary systemic amyloidosis from heart and/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 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. However, in most cases lesions recur.

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.

Related information

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