Amyloidosis, primary localized cutaneous, 3

Amyloidosis cutis dyschromica (ACD), a rare form of primary localized cutaneous amyloidosis, is a pigmentary disorder in which keratinocyte-derived amyloid is deposited in the skin. Onset occurs before puberty and involves macular or reticulate hyperpigmentation admixed with symmetrically distributed guttate hypopigmented and hyperpigmented lesions. ACD can be distinguished from other conditions with similar clinical findings by a skin biopsy in which amyloid deposition in the papillary dermis is seen. Specific features that set ACD apart from the more common macular and lichenoid variants of primary cutaneous amyloidosis include dotted, reticular, or diffuse hyperpigmentation admixed with lentil-sized hypopigmented macules; mild or no associated pruritus; and, on histologic examination of skin from both hyper- and hypopigmented lesions, amyloid deposition confined to the papillary dermis, in close proximity to the epidermis (Huang et al. (2009); Mahon et al., 2016). For a discussion of genetic heterogeneity of primary localized cutaneous amyloidosis, see 105250. [from OMIM]