An intensely pruritic pebbled presentation.Dermatol Online J. 2018 Mar 07; 24(2)DO
Lichen amyloidosis (LA) is a form of primary localized cutaneous amyloidosis (PLCA) characterized by bilateral intensely itchy domed scaly hyperkeratotic papules. Lichen amyloidosis is rare and affects men more than women. It is uncommonly seen in the western world but more prevalent in Asia. These papules most typically affect the shins and occasionally the arms and torso. Lichen amyloidosis has been reported in association with autoimmune disorders and after prolonged exfoliation and friction of affected skin. We present a 40-year-old woman with LA. In LA, the characteristic histological finding is apple-green birefringence of Congo red-stained preparations observed under polarized light. However, this is not always strongly positive, as in our patient. Other findings may include eosinophilia, periodic acid-Schiff positivity, staining with thioflavin T, and metachromasia after staining with crystal violet or methyl violet. Treatment of LA is difficult and complete clinical remission is seldom achieved. Recent trials revealed beneficial outcomes with topical calcipotriol, phototherapy, acitretin, cyclophosphamide, and laser treatments. A combination of acitretin, antihistamines, topical steroids, and hydrocolloid dressings have been beneficial in our patient with LA.