Amyloidosis



Amyloidosis


Kajsa Affolter, MD










Amyloid is an amorphous, acellular, eosinophilic substance image as seen on H&E section in this case of nodular amyloidosis.






In this image, amyloidosis is demonstrated by waxy indurated papules image on the eyelids. There is also a shave biopsy site on the right upper eyelid image, which confirmed the diagnosis.


TERMINOLOGY


Definitions



  • Generic term denoting extracellular tissue deposition of eosinophilic fibrils composed of altered autologous proteins


ETIOLOGY/PATHOGENESIS


6 Important Amyloid Proteins in Cutaneous Pathology



  • Amyloid light chain (AL) is derived from immunoglobulin light chains


  • Amyloid A protein (AA) is an HDL3-associated lipoprotein and an acute phase reactant


  • Amyloid transthyretin protein (ATTR) is present in certain heritable amyloidosis syndromes


  • Aβ-2-microglobulin protein induced by β-2-microglobulin glycosylated polypeptide


  • Amyloid keratin protein (AK) in primary cutaneous amyloidosis derived from filamentous degeneration of keratin filaments


Systemic Amyloidosis (SA)



  • Primary systemic amyloidosis; often involves skin



    • Deposition of AL (kappa or lambda)


    • May be multiple myeloma (MM) associated


    • Occurs in approximately 1/3 of patients with MM


  • Secondary systemic amyloidosis



    • Usually no skin involvement


    • Deposition of AA, amyloid A, or derived from β-2-microglobulin following long-term hemodialysis


  • Heritable amyloidosis



    • Includes entities such as familial Mediterranean fever, Muckle-Wells syndrome, familial cold autoinflammatory syndrome, and familial amyloidotic polyneuropathy


  • Amyloid elastosis



    • Rare entity with cutaneous lesions and progressive systemic disease


Primary Localized Cutaneous Amyloidosis (PLCA)



  • Macular amyloidosis (MA)



    • Deposition of AK, amyloid keratin protein, which is a keratin intermediate filament


  • Lichen amyloidosis (LA)



    • Deposition of amyloid keratin protein (AK), which is a keratin intermediate filament


  • Nodular amyloidosis (NA)



    • Deposition of amyloid light chain (AL) has been shown in many cases


  • Poikilodermatous amyloidosis



    • Rare form of localized cutaneous amyloidosis


  • Anosacral amyloidosis



    • Rare form of localized cutaneous amyloidosis


CLINICAL ISSUES


Epidemiology



  • Age



    • PLCA: Predominantly adult population with earliest cases appearing around puberty


  • Gender



    • MA: Affects females more than males


    • LA: Affects genders equally


  • Ethnicity



    • SA: In developed countries, AL is most frequently deposited precursor protein, whereas in developing countries AA is most frequently deposited precursor protein


    • MA is seen with increased frequency in patients from Middle East, Asia, and Central and South America


    • LA is seen with increased frequency in patients from Southeast Asia



Presentation

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Amyloidosis
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