Amyloid:

-a group of substances with B-pleeted sheet configuration.

-eosnophilic appearance, located extracellularly proximate to basement membranes

-stain with Congo red, has apple green birefringence

 

Clinical Patterns

-Primary amylodisos (immuncytic dyscrasia): AL protein (derived from immuglobulin light chains) à deposits in heart, muscle, tongue, kidney

            - associated with plasma cell disorders (multiple myeloma, waldenstrom macroglobulinemia)

 

-Secondary amyloidosis (ractive systemic): AA protein. Chronic tissue destruction à increase in SAA (serum amyloid-associated protein)à deposition of fibrils consisting of amyloid protein (called AA protein) in parenchymous organs.

-“saga spleen”: perifollicular involvement resulting in a spleen that looks like tapioca granules.

 

Other forms

-Portugeues type of polyneuropathy: derived from Transthyretin (a protein that transports thyroxine and retinol). Characterized by peripheral nerve involvment.

-Alzheimer disease: A4 amyloid (or AB-portein). Chromosome 21

-Familial medicteranean fever: AA amyloid. Autosomal recessive disease.

-Medullary carcinoma of thyroid: Amyloid protein from calcitonin deposits within the tumor

-Diabetes mellitus: amylin deposits in islet cells

-Senile amyloidosis : found during autopsy in brain, heart. Transthyretin

-Dialysis-associated : amyloid depsoits in joints. derived from B-microglobulin