Skin nontumor

Dermal collagen and elastic tissue alterations, and cutaneous deposits


Last author update: 1 July 2011
Last staff update: 29 July 2021

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PubMed Search: Amyloidosis [title] skin

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Amyloidosis. website. Accessed September 22nd, 2023.
Clinical features
  • In primary localized cutaneous amyloidosis, by definition, there is no systemic or other dermatologic disorder
  • Either macular (Central / South America, India, Middle East), lichenoid (China), biphasic or nodular
  • Macular: moderately pruritic dark brown papules in reticulated or rippled pattern, symmetric over upper back and arms
  • Lichenoid: intensely pruritic, discrete, firm, hyperkeratotic plaques and papules of anterior shins and extensor forearms, with amyloid deposits in papillary dermis accompanied by hyperkeratosis, papillomatosis and epidermal hyperplasia
  • Biphasic: lichenoid and macular
  • To differentiate between amyloid AA and other types, use potassium permanganate reaction; amyloid AA does not stain with Congo Red after potassium permanganate, but others do (Am J Pathol 1979;97:43)
Case reports
Clinical images

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Facial involvement

Microscopic (histologic) description
  • Primary amyloidoisis: masses of eosinophilic, amorphous, fissured material in dermis and subcutaneous tissue
  • Macular amyloidosis: focal / small amounts of eosinophilic faceted deposits in papillary dermis; also pigment incontinence
  • Lichenoid amyloidosis: hyperkeratosis, acanthosis, basal hydropic degeneration; small eosinophilic globules in papillary dermis; also mild chronic inflammatory cell infiltrate, pigment incontinence
Microscopic (histologic) images

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Various images

Congo Red staining without (left) and with (right) polarization microscopy

Congo Red staining (left) and Thioflavin-T staining with fluorescent microscopy (right)

Positive stains
  • Congo Red shows apple-green birefringence under polarized light
  • Methyl or cresyl violet
  • Thioflavin T with examination using fluorescence microscopy
Electron microscopy description
  • Straight non branching amyloid filaments with a diameter of 6 - 10 nm showing a hollow core on cross section
  • Infra red microscopy reveals a beta pleated antiparallel configuration
Electron microscopy images

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Mesh-like pattern consisting of 6 - 10 nanometer nonbranching fibrils diagnostic of amyloid

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