Lichen amyloidosis is the most common type of primary cutaneous amyloidosis.
Amyloidosis is a rare condition characterized by the extracellular deposition of amyloid in various organs.
Lichen amyloidosis is a type of primary cutaneous amyloidosis, in which the amyloid deposits bind to antikeratin antibodies causing the deposition of amyloid in the papillary dermis.
Macular and nodular amyloidosis are the other types of primary cutaneous amyloidosis. Macular and lichen amyloidosis may be present simultaneously leading to biphatic amyloidosis.
The cause of lichen amyloidosis is not known, although both environmental and genetic factors may be involved.
However, lichen amyloidosis is not associated with systemic amyloidosis.
Lichen amyloidosis may be associated with the following systemic conditions:
- primary biliary cirrhosis;
- systemic lupus erythromatosis;
- multiple endocrine neoplasia type 2A (Sipple’s syndrome) characterized by the thyroid medullary carcinoma, pheochromocytoma, and parathyroid disorder;
- Sjögren’s syndrome is characterized by the dry mouth and dry eyes.
Usually native Chineses are affected. The disorder is more likely to develop in males at the age between 50 and 60 years.
Lesions in lichen amyloidosis itch extremely.
Lichen amyloidosis initially presents as multiple discrete, pruritic, firm, scaly, hyperkeratotic raised spots called papules, red-brown in color. Commonly the lesions appear on the shins and other extensor sides of the thighs, feet or forearms. The face, chest and abdomen are involved rarely.
Later the papules coalesce forming thickened plaques with rippled pattern. Initially, only one side is affected and then gradually distribute symmetrically.
Excessive scratching may lead to the bleeding and pain.
Treatment of macular amyloidosis includes both conservative and surgical measures.
Ultraviolet B (UV-B) light (narrow band and broadband) and PUVA (psoralen with UVA) phototherapy may be performed at least for 8 weeks as a symptomatic treatment.
If the previous treatment wasn’t effective dermabrasion, CO2 laser, and laser vaporisation are used as an alternative measure.
Lesion excision or electrodedesiccation was suggested as an aggressive surgical treatment.
Medicines administered in the treatment of macular amyloidosis include the following:
- Topical corticosteroids (0,1% Betamethasone 17-valerate ointment);
- Topical anti-inflammatory agents such as Dimethyl sulfoxide (10-100%);
- Topical calcineurin inhibitors (0.1% Tacrolimus oinment);
- Intralesional corticosteroids (Triamcinolone);
- Systemic retinoids (Acitretin, etretinate, topical tocoretinate);
- Systemic cyclophosphamide 50 mg per day;
- Cyclosporine 4mg/kg per day for at least 12 months;
- Sedating antihistamines (Chlorpheniramine, Diphenhydramine) are recommended to reduce the itching;
- Menthol may be used along with the antihistamines to reduce the pruritus.