Amyloidosis most commonly affects

Amyloidosis*A disease due to an accumulation of abnormal proteins which are formed due to abnormal protein misfolding. *Light microscopy: Amorphous, eosinophilic, hyaline, extracellular substance that causes atrophy of adjacent cells*Congored stain: Pink or red color to amyloid deposits*Congored under polarized microscopy: Apple green birefringence*To differentiate primary amyloidosis from secondary amyloidosis: Treat with potassium permanganate and then perform congo red stain. Congo red stain show positive in primary amyloidosis but negative in secondary amyloidosis due to potassium permanganate treatment. (Primary-persists) *Electron microscopy: Continous non-branching fibril with a diameter of 7.5 to 10nm*X-ray crystallography and Infrared spectroscopy- cross beta-pleated sheet conformation*Most common organs involved: Kidney and Hea *Most common test performed to diagnose amyloidosis: Abdominal fat pad aspiration*Most reliable test performed to diagnose amyloidosis: Tissue biopsy*Most rapid test to diagnose amyloidosis: Scintigraphy with radiolabelled serum amyloid O component*Test used in treatment follow up: Scintigraphy with radiolabelled serum amyloid O componentRef: Robbins 8/e p249