AMYLOID: PATHOLOGY

MUSCLE

Congo red stain	Congo red stain	Congo red stain (Polarized light)
Amyloid myopathy Amyloid (red) is deposited along muscle fiber surfaces and in the perimysium Apple green birefringence of amyloid (Right)

Congo red

Congo red (Polarized light)

Congo red (Fluorescence)

• Mild change (Above): Thin layer of amyloid around normal sized muscle fiber
• More severe change (Below): Thick deposit of amyloid around small muscle fibers

Congo red

Congo red (Polarized light)

Congo red (Fluorescence)

Congo red

Congo red

• Abnormal nuclei in ring around periphery of muscle fibers
• Irregular deposit of amyloid around muscle fibers

NERVE

Congo red stain	Congo red stain
Amyloid neuropathy Amyloid is deposited in endoneurial blood vessels
Toluidine blue stain	Toluidine blue stain
Amyloid neuropathy Most small myelinated axons are lost. Larger myelinated axons are relatively preserved. Amyloid is deposited in a vessel wall (arrow) and damages its architecture.

Moderate sized vessels: Amyloid

Congo red stain	Congo red stain (Polarized light)
Amyloid in vessel wall is stained red.	Amyloid in vessel wall is apple green when viewed with fully polarized light.
View amyloid birefringence