| • | "amyloid" = “starch” like |
AL vs. AA vs. keratin amyloid:
OR (Primary Systemic vs. Secondary Systemic vs. Cutaneous Amyloid):
AL:
| • | Bence-Jones protein in urine |
| • | renal, restrictive myopathy, macroglossia, pinch purpura (because fragile capillaries) |
| • | if no gammopathy, then “primary systemic amyloidosis” |
“SECONDARY SYSTEMIC AMYLOIDOSIS”:
| • | AA = a reactive protein derived from serum amyloid-A ( an alpha-globulin in normal serum) |
| • | chronic inflammatory or infectious diseases ex. RA, FMF, osteomyelitis, bronchiectasis, lepromatous leprosy |
| • | predilection sites of AA deposition = parenchymatous organs (kidney, liver, spleen) |
| • | (-) congo red after treatment with potassium permanganate (vs. AL or keratin amyloid) |
Muckle-Wells syndrome:
| • | fever, urticaria, renal amyloid (AA), nerve deafness |
Familial meditarranean fever:
| • | AA amyloid; erysipelas-like lesions on legs |
IDIOPATHIC KERATIN AMYLOIDOSIS:
(seems to be caused by scratching the skin)
LICHEN AMYLOID
| • | extensor surfaces of extremities (shins) |
| • | amyloid derived from epidermis (essentially a variant of LSC) |
| • | deposits high in papillary dermis |
| • | ddx: LSC, woody lymphedema, pretibial myxedema |
| • | treatment pearl - cover with duoderm (x months) |
see Amyloid
|
macular amyloid
| • | classically wavy hyperpigmentation on an itchy back (can be seen unilaterally in patients with notalgia paresthetica) |
Stains:
| • | congo red à green birefringence in polarized light |
| • | crystal violet à red metachromasia |
| • | thioflavin t à yellow-green fluorescence under fluorescent microscope |
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