Itchy Pigmented Lesions on the Upper Back
Macular amyloidosis is a common primary localized cutaneous amyloidosis developing due to deposition of keratinocytes-derived amyloid proteins in previously normal appearing skin. A 40-year-old lady presented with itchy hyperpigmented macules and patches on the upper back and upper extremities of 2 years duration. The lesions were arranged in a characteristic rippled pattern. Dermoscopy showed the presence of brown clods with radiating brown lines, in a “Hub and Spoke” pattern. The diagnosis of macular amyloidosis was confirmed on histopathology by demonstrating eosinophilic, amorphous deposits in papillary dermis which stain positive for amyloid with Congo red stain. Treatment is often disappointing and topical corticosteroids, 10% dimethylsulphoxide (DMSO), acitretin and dermabrasion have been tried with variable success.
KeywordsPrimary localized cutaneous amyloidosis Macular amyloidosis Amyloid protein Hub and Spoke pattern Congo red Dimethylsulphoxide