Amyloidotic

Amyloidotic is an adjective used in pathology to describe tissue or a condition characterized by amyloid deposition. Amyloid refers to insoluble protein aggregates formed by misfolded proteins that accumulate extracellularly, often in a beta-pleated sheet configuration. When tissues show amyloid deposits, they may be described as amyloidotic.

Amyloid originates from various precursor proteins. The most common systemic forms are AL (light-chain) amyloidosis, AA (amyloid A) related to chronic inflammation, and ATTR amyloidosis from transthyretin. Others include Aβ2M associated with long-term dialysis. Deposits can be systemic, affecting multiple organs, or localized to a single site such as the skin or larynx.

Clinical impact depends on organ involvement. Cardiac amyloid deposition can cause restrictive cardiomyopathy; kidney involvement may lead to nephrotic syndrome; liver enlargement; peripheral or autonomic neuropathy; and gastrointestinal symptoms. Diagnosis relies on tissue biopsy with Congo red staining showing apple-green birefringence under polarized light, with further typing by immunohistochemistry or mass spectrometry; additional laboratory studies assess precursor proteins and evaluate organ function.

Treatment aims to limit production of the amyloidogenic precursor or stabilize the responsible protein and to manage organ dysfunction. For AL amyloidosis, chemotherapy or stem cell transplantation may be used; AA amyloidosis targets the underlying inflammatory condition; ATTR amyloidosis has disease-specific therapies that reduce transthyretin production or stabilize the protein. Supportive care for heart, kidney, and nerve involvement is essential. The prognosis varies with amyloid type and organ burden.