Cutaneous Amyloidosis

Amyloidosis or ‘amyloid’ is a group of rare diseases in which abnormal proteins accumulate in various organs, including the skin. The name ‘amyloid’ was given to the condition over 150 years ago because the deposits looked like starch under the microscope. (In Latin amylum = starch).

In primary localized cutaneous amyloidosis (PLCA) amyloid deposits only occur in the skin.  It usually starts in adult life and tends to persist for many years.

There are three main forms of PLCA: Macular amyloidosis, lichen / papular amyloidosis, and Nodular amyloidosis (the rarest condition).

The cause of PLCA is not known. The most familiar trigger is repeated scratching and rubbing of the skin, such as in chronic atopic eczema.

Macular and papular (lichen) amyloidosis is usually itchy, but nodular amyloidosis does not usually cause any symptoms.

Macular amyloidosis is most often seen on the upper back in a symmetrical distribution as greyish-brown, slightly thickened skin. The pigment may have a rippled appearance. 

Lichen amyloidosis appears as clusters of small skin-colored, reddish, or brown scaly spots, which can merge to form raised thickened areas, especially on the shins and lower limbs.

When a diagnosis of cutaneous amyloid is suspected, a skin biopsy (tissue sample) may be taken under local anesthetic to confirm the diagnosis.

Unfortunately, there is no cure for PLCA. Treatments aim to reduce the symptoms.

Many different treatments have been tried, but extensive studies are lacking, and there is no preferred therapy. For lichen amyloidosis and macular amyloidosis, the treatments are similar to those used for eczema. They include antihistamine tablets, corticosteroid creams, and ointments, vitamin D ointment (e.g., calcipotriol), and ultra-violet light (Phototherapy). 

Oral medication options include a derivative of vitamin, colchicine, ciclosporin (an immune-suppressive drug), and low doses of amitryptiline (an antidepressant drug).

Lesions of nodular amyloidosis can be surgically removed if causing symptoms, but they often re-grow. Excision, curettage, and cautery (scraping the lump off and stopping the bleeding with heat or destroying skin with ‘ablative’ lasers) require a local anesthetic injection. Cryotherapy can be done without local anesthetic. Steroid injections may help to shrink the lumps.

Friction can aggravate lichen and macular amyloidosis, so try to avoid rubbing or scratching the skin. A non-prescription menthol-containing cream can be used for instant itch relief. Habit reversal techniques may also help to reduce scratching behavior. Any associated dryness of the skin should be managed with regular reduction of moisturizers and soap substitutes.