Skin nontumor
Dermal collagen and elastic tissue alterations and metabolic disorders
Amyloidosis
Last author update: 1 July 2011
Last staff update: 29 July 2021
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PubMed Search: Amyloidosis [title] skin
Table of Contents
Clinical features | Case reports | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Electron microscopy description | Electron microscopy images | Additional referencesCite this page: Hamodat M. Amyloidosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumoramyloidosis.html. Accessed April 24th, 2024.
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
- 27 year old man with hyperpigmented black patches on upper back and limbs (Arch Pathol Lab Med 2005;129:697)
- 72 year old woman with 20 year history of easy eyelid bruising (Dermatology Online Journal 1995;1(2))
Clinical images
Images hosted on other servers:
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
Images hosted on other servers:
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
Additional references
