Histopathology of Cutaneous Amyloid: A Comparative Study on 144 Cases of Localized Cutaneous Amyloidosis and 20 Cases of Systemic Amyloidosis

Abstract

Skin specimens from 164 patients were studied, including 20 cases of systemic and 144 cases of localized cutaneous amyloidosis.

In localized cutaneous amyloidosis, subepidermal amyloid deposits were noted only in the papillae (136/144), the subpapillary layer (75/144) and the uppermost part of the reticular layer (2/144). Mesenchymal cells in the amyloid deposits, intraepidermal amyloid fragments and pigmentary incontinence were detected in 102, 43 and 121 cases respectively.

In systemic amyloidosis, amyloid deposits were detected in 17 of the 20 cases, whose protein was identified by PAP method as Aλ (4/17), AA (6/17), AA + Aκ (2/17) and was unidentifiable in the rest. They were discerned in the papillae (2/17), the subpapillary layer (5/17), the reticular layer (4/17), the subcutaneous fatty tissue (6/17), around the appendages (7/17) and on the walls of vessels (16/17). Intraepidermal amyloid fragments (2/17), mesenchymal cells in amyloid (4/17) and pigmentary incontinence (2/17) were noted less frequently than in localized cutaneous amyloidosis.

It would appear that in systemic amyloidosis, skin involvement bears no reference to the property of amyloid protein and that the manner in which amyloid is deposited is not relevant in distinguishing localized cutaneous amyloidosis from systemic amyloidosis, except for the different distribution of the substances.