Amyloidosis

Epidemiology

• Extracellular deposit of insoluble polymeric protein fibrils in tissue & organs
• Can be primary (AL type) or secondary (AA) to chronic inflammatory conditions such as:
• Inflammatory arthritis (e.g RA)
• Chronic infections (e.g bronchiectasis, tuberculosis, osteomyelitis)
• Inflammatory bowel disease (e.g Crohn's disease)
• Malignancy (e.g. lymphoma)
• Vasculitis

Clinical presentation

• Asymptomatic proteinuria or nephrotic syndrome 
• Restrictive cardiomyopathy
• Hepatomegaly
• Peripheral neuropathy &/or autonomic neuropathy
• Visible organ enlargement (e.g. macroglossia)
• Bleeding diathesis
• Waxy thickening, easy bruising of skin

Diagnosis 

• Tissue biopsy (e.g. abdominal fat pad)

Congo red stain shows amyloid deposits within vessel walls. 

Congo red stain shows apple green birefringence under polarized light.