Amyloidosis

Published on 18/03/2015 by admin

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Amyloidosis

William Y-M Tang and Loi-yuen Chan

Evidence Levels:  A Double-blind study  B Clinical trial ≥ 20 subjects  C Clinical trial < 20 subjects  D Series ≥ 5 subjects  E Anecdotal case reports

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Amyloid is an altered, insoluble protein that can accumulate in one or many organs, causing dysfunction. Primary localized cutaneous amyloidosis is characterized by the deposition of amyloid in the skin without involving any internal organ. It occurs more commonly in Southeast Asian, Chinese, Middle Eastern, and South American people. There are three clinical forms: lichen, macular, and nodular. The co-occurrence of macular and lichen amyloidosis in a patient is known as biphasic amyloidosis. The amyloid in macular and lichen amyloidosis is derived from degenerated keratinocytes, whereas in nodular amyloidosis it is derived from immunoglobulin light chains from a local plasma cell clone.

Lichen amyloidosis (see Figure) is a persistent eruption of multiple red-brown hyperkeratotic papules often affecting extensor aspects of extremities, especially the pretibial surfaces. It appears more commonly in males. Apart from its cosmetic nuisance, marked itching can occur. Although familial cases of lichen amyloidosis have been reported, most cases occur as isolated events having no association with systemic disease.

Macular amyloidosis is characterized by an eruption consisting of small, dusky-brown or grayish pigmented macules distributed symmetrically over the upper back and upper arm. It has a reticulated or rippled pattern. Itch is variable, and patients often seek medical advice for aesthetic issues and pruritus.

Nodular amyloidosis is the rarest subtype. It is characterized by single or multiple waxy, firm, brown or pink nodules involving the legs, head, trunk, arms, and genitalia. It is usually asymptomatic.

Management strategy

Lesions of localized cutaneous amyloidosis can produce considerable pruritus. Patients seek treatment to alleviate pruritus and the undesirable appearance. Currently there are no accepted standard treatments for the various types of cutaneous amyloidosis because of a lack of good clinical trials. As pruritus is a common symptom, antihistamines and topical corticosteroids are prescribed as first-line treatments.

Phototherapy (UVB or PUVA) has been used to treat lichen amyloidosis successfully for relief of pruritus. Acitretin may be added for combined therapy. Laser treatments reported to be successful in treating cutaneous amyloidosis include carbon dioxide, pulsed-dye (PDL) and neodymium:yttrium aluminum garnet (Nd:YAG).

Dermabrasion has been successful in treating lichen and nodular amyloidosis. This improves cosmesis and alleviates pruritus, but brings accompanying procedural pain and the development of skin atrophy. There is an anecdotal report that dermabrasion of lichen amyloidosis under tumescent anesthesia can result in remarkable pain reduction even though the total amount of local anesthetic required is low.

Other treatment choices include tacrolimus, transcutaneous electrical nerve stimulation (TENS) and tocoretinate. Topical dimethylsulfoxide (DMSO) also has been reported to benefit lichen and macular amyloidosis. However, a more recent study on 25 patients reported lack of efficacy.

Second-Line therapies

image Phototherapy/photochemotherapy D
image Oral retinoids D
image Laser D
image Dermabrasion E
image Tacrolimus E
image Excision E
image Transcutaneous electrical nerve stimulation D
image Tocoretinate D

Comparative study of phototherapy (UVB) vs. photochemotherapy (PUVA) vs. topical steroids in the treatment of primary cutaneous lichen amyloidosis.

Jin AG, Por A, Wee LK, Kai CK, Leok GC. Photodermatol Photoimmunol Photomed 2001; 17: 42–3.

In this study, 14 patients with lichen amyloidosis were treated with either UVB (n = 9) or PUVA (n = 5) to half of the body, applying potent topical corticosteroids to the other half as a control. After 8 weeks of treatment, patients treated with phototherapy had more improvement in average roughness of lesions and itch than on the control side. Improvement of roughness in the UVB-treated lesions was significant. However, the difference in improvement in itch in the UVB- and PUVA-treated lesions compared to the control lesions was not significant.

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