Primary localized cutaneous amyloidosis.

Fifty-seven patients with primary localized cutaneous amyloidosis (PLCA) were clinically and histopathologically reviewed. Two-thirds of patients had macular amyloidosis (MA). Intermediate cases having macular lesions with micropapules and/or lichens were identified. A spectrum for the disease is proposed, in which the less itchy classical macular variant occurs at one end and the very pruritic traditional lichen variant at the other. The salient histopathologic findings were similar in the macules, micropapules, and lichens, but were more prominent in the lichens. These consisted of hyperkeratosis, keratinocyte degeneration, satellite cell necrosis, and basal cell destruction. Amyloid deposition in the dermal papillae with transepidermal elimination, dermal melanophages, and superficial perivascular inflammation were also present. These changes represent an interface dermatitis of the vacuolar type. PLCA may be categorized under the group of dermatoses characterized by a lichenoid tissue reaction; inflammation may play a key role in mediating these disorders.