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== Overview ==
== Overview ==


==Historical Perspective==
==Historical Perspective==
In 1639, Nicolaus Fontanus [[Autopsy|autopsied]] a young man who had [[ascites]], [[jaundice]], [[liver abscess]], and [[splenomegaly]] and his report has been the first description of amyloidosis. There is no significant data regarding the historical perspective of amyloidosis throughout the 18th century. Rudolph Virchow and Weber are the prominent figures with substantial work on amyloidosis during the 19th century. In 1922, Bennhold introduced [[Congo red|Congo Red staining]] of [[amyloid]] that remains the [[Gold standard (test)|gold standard]] for [[diagnosis]].


==Classification==
==Classification==
The more common types of amyloid include AL, AA, , ATTR and Aβ<sub>2</sub>M from the 15 biologically distinct forms.  
Amyloidosis may be classified on the basis of type of amyloidogenic protein and associated clinical syndromes into primary (AL) amyloidosis, secondary (AA) amyloidosis, familial (AF) amyloidosis, transthyretin (ATTRwt) amyloidosis and dialysis-associated (AH) amyloidosis. It can also be classified based on extent of [[organ system]] involvement


==Pathophysiology==
==Pathophysiology==
[[Amyloid]] is a pathological extracellular deposit composed predominantly of amyloid fibrils. Amyloidosis is disease caused by amyloid deposits in the tissues. The deposits may be local or systemic in distribution and acquired or hereditary in aetiology. All patients with amyloidosis have amyloid deposits in their tissues when they first present clinically. Clinical impairment progresses as amyloid deposits increase in size, and regression of amyloid is associated with clinical improvement and survival. Secondary amyloidoses is far more common than the primary amyloidoses.
[[Amyloid]] is an abnormal insoluble [[extracellular]] [[protein]] that deposits in the different tissues and causes organic dysfunction and a wide variety of clinical syndromes. In systemic amyloidosis, [[amyloid]] gradually accumulate and [[amyloid]] deposition is widespread in the viscera, [[blood vessel]] walls, and in the different [[Connective tissue|connective tissues]]. [[AL amyloidosis|Primary (AL) amyloidosis)]] is the most common type of amyloidosis. It results from aggregation and deposition of monoclonal [[Immunoglobulin|immunoglobulin (Ig)]] [[Light chain|light chains]] that usually produced by [[plasma cell]] clones. [[AA amyloidosis|Secondary amyloidosis]] is associated with chronic [[inflammation]] (such as [[tuberculosis]] or [[rheumatoid arthritis]]). Hereditary (or familial) amyloidosis are [[Autosome|autosomal]] [[Dominance relationship|dominant]] diseases that [[inherited]] variant [[Protein|proteins]] cause the production and deposition of [[amyloid]] fibrils. Some [[Neurodegenerative disease|neurodegenerative disorders]]<nowiki/>such as [[Parkinson's disease]], [[Alzheimer's disease|Alzheimer]], and [[Huntington's disease]] may occur in localised amyloidosis. On microscopic pathology, typical green [[birefringence]] under [[Polarization|polarized]] light after [[Congo red]] staining (appears in red under normal light)


==Causes==
==Causes==
Amyloidosis is can be systemic or organ specific. In systemic amyloidosis, secondary variety (AL, AA) is far more common than the primary one.
Hereditary amyloidosis can be caused by [[genetic mutations]] in different genes. Causes of acquired amyloidosis can include [[tuberculosis]], [[Familial mediterranean fever|familial Mediterranean fever]], [[rheumatoid arthritis]], [[multiple myeloma]], [[ankylosing spondylitis]], and [[psoriatic arthritis]].


==Differentiating Amyloidosis from other Diseases==
==Differentiating Amyloidosis from other Diseases==
Amyloidosis needs to be differentiated from acute [[myocarditis]], [[bronchiectasis]], [[multiple myeloma]] and other systemic diseases .
Amyloidosis needs to be differentiated from acute [[myocarditis]], [[bronchiectasis]], [[multiple myeloma]] and other systemic diseases .
== Epidemiology and Demographics ==
The [[incidence]] of amyloidosis is approximately 1.2 per 100,000 individuals per year worldwide. The [[prevalence]] of AL amyloidosis increased significantly between 2007 and 2015, from 1.6 per 100,000 in 2007 to 4.0 per 100,000 in 2015. The [[mortality rate]] of systemic amyloidosis is approximately 100 per 100,000 deaths in developed countries. In amyloidosis, the mean age of presentation is 55 - 60 years. Men are more commonly affected by amyloidosis than women.


==Risk Factors==
==Risk Factors==
Risk factors have not yet been identified.
There are no established risk factors for amyloidosis. Some inflammatory conditions might increase the likelihood of [[amyloid]] deposition in the body.


==Screening==
==Screening==
There is insufficient evidence to recommend routine [[Screening (medicine)|screening]] for amyloidosis.


==Natural History, Complications and Prognosis==
==Natural History, Complications and Prognosis==
The complications of amyloidosis include hyposplenism, [[malabsorbtion syndrome]], [[myopathy]], [[proximal renal tubular acidosis]] and [[renal failure]]. The severity the disease depends on the organs that are affected. When the heart and kidney are involved, it may lead to organ failure and death.
In amyloidosis, insoluble fibrils of [[amyloid]] are deposited in [[organs]], causing [[Multiple organ dysfunction syndrome|organ dysfunction]] and eventually death. [[Patient|Patients]] with amyloidosis may eventually suffer from [[heart failure]], [[nephrotic syndrome]], [[hepatomegaly]] and [[peripheral neuropathy]]. In primary amyloidosis, the [[survival rate]] depends upon the type of [[Organ (anatomy)|organ]] involvement and the [[hematological]] response to treatment. In AL amyloidosis, untreated individuals have the worst [[prognosis]]. In this group of patients, the [[median]] [[Survival rate|survival]] is one to two years.
 
===Natural History===
 
===Complications===
 
===Prognosis===


==Diagnosis==
==Diagnosis==


===Diagnostic Criteria===
===Diagnostic Study of Choice===
The diagnostic study of choice in amyloidosis is [[Tissue (biology)|tissue]] [[biopsy]] of the affected [[Organ (anatomy)|organ]]. [[Congo red|Congo Red staining]] will show apple green birefringence of the tissue sample under polarized light, and subtyping of [[Light chain|light chains]](for light chain amyloidosis) can be done via [[mass spectrometry]]. [[Bone marrow biopsy]] and organ-specific laboratory measurements are also important ancillary [[Test|tests]].


===History and Symptoms===
===History and Symptoms===
Symptoms depend on the organs affected by the deposits. These organs can include the tongue, intestines, skeletal and smooth muscles, nerves, skin, ligaments, heart, liver, spleen, and kidneys.
In amyloidosis, the range of [[symptoms]] depends on specific [[Tissue (biology)|tissues]] and [[organs]] involved. [[Symptoms]] can be quite diverse.


===Physical Examination===
===Physical Examination===
Common findings in amyloidosis include [[petechiae]], [[ecchymosis]], [[parotid gland]] enlargement, increased [[intra ocular pressure]], enlarged tongue, [[hepatomegaly]], [[carpal tunnel syndrome]] and [[Raynaud phenomenon]].
Common findings in amyloidosis include [[petechiae]], [[ecchymosis]], [[parotid gland enlargement]], increased [[intraocular pressure]], [[enlarged tongue]], [[hepatomegaly]], [[carpal tunnel syndrome]], and [[Raynaud's phenomenon]].


===Laboratory Findings===
===Laboratory Findings===
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===Electrocardiogram===
===Electrocardiogram===
EKG findings in a case of amyloidosis include an abnormal rhythm and [[low voltage recordings]].
[[Electrocardiogram]] is particularly useful for cardiac amyloidosis. Findings on [[electrocardiogram]] include low voltage [[QRS complexes]], left and right ventricular [[Hypertrophy (medical)|hypertrophy]], [[Left atrium|left atrial]] abnormalities, pathological [[Q wave|Q waves]], and [[Atrioventricular block|AV block]].
 
===Chest X-Ray===
[[Chest x-ray]] findings in a case of amyloidosis include a coin lesion.


===Chest X Ray===
=== CT Scan ===
The X ray findings in a case of amyloidosis include a coin lesion.
[[Computed tomography|CT scan]] can be done to assess for [[amyloid]] deposition in particular [[organs]]. It can also be done to rule out other causes of [[Organ failure|organ dysfunction]]. However, [[MRI]] is more sensitive than [[CT-scans|CT]] in the diagnosis of amyloidosis.


===MRI===
===MRI===
Cardiac [[MRI]] is used when [[echocardiogram]] fails to differentiate amyloidosis from [[hypertrophic cardiomyopathy]].
[[MRI]] is commonly done to assess for [[amyloid]] deposition in particular organs. It can also be done to rule out other causes of organ dysfunction. A cardiac [[MRI]] is used when an [[echocardiogram]] fails to differentiate amyloidosis from [[hypertrophic cardiomyopathy]].


===Echocardiography===
===Echocardiography===
Echocardiography is useful to evaluate extent of heart involvement. The common findings include thickened ventricular wall and wall motion abnormalities.
[[Echocardiography]] is critical in the [[diagnosis]] of cardiac amyloidosis. [[Echocardiogram]] should be done at [[diagnosis]] and routinely thereafter to monitor response to therapy.


===Other Imaging Findings===
===Other Imaging Findings===
Tissue Doppler and myocardial strain rate imaging has been proven to be very sensitive for the assessment of myocardial dysfunction in [[restrictive cardiomyopathy]]. [[Serum amyloid P component]] (SAP) scans have been developed which can anatomically localize amyloid deposits.
Tissue [[doppler]] echocardiography and myocardial strain rate imaging has been shown to be very sensitive for the assessment of myocardial dysfunction in [[restrictive cardiomyopathy]]. The developmend of [[serum amyloid P component]] (SAP) scans has given physicians the ability to specifically locate [[amyloid]] deposits.


===Other Diagnostic Studies===
===Other Diagnostic Studies===
A tissue [[biopsy]] or fat [[aspirate]] should be done to confirm the presence or type of [[amyloid]] protein which is involved in the [[pathogenesis]] of the disease.


==Treatment==
==Treatment==
Line 69: Line 71:


===Medical Therapy===
===Medical Therapy===
There are few available treatments for primary amyloidosis. Since the disease is typically discovered at an advanced stage, the initial treatment is aimed at preventing further [[Organ (anatomy)|organ]] damage and correcting the effects of [[organ failure]]. The most commonly used regimen for AL amyloidosis is CyBorD, which consists of [[cyclophosphamide]], [[bortezomib]], and [[dexamethasone]].


===Surgery===
===Surgery===
[[Organ transplant|Organ-specific transplant]] may need to be done, depending on the organ involved. However, [[surgery]] is not commonly done in patients with amyloidosis, since it is usually a systemic disease that requires treatment of the underlying cause.
==Prevention==
=== Primary Prevention ===
There is no role for [[primary prevention]] in amyloidosis.


===Prevention===
=== Secondary Prevention ===
There is no role for secondary prevention in amyloidosis.


==References==
==References==

Latest revision as of 04:50, 21 November 2019

Amyloidosis Microchapters

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Overview

Historical Perspective

Classification

Primary amyloidosis
Secondary amyloidosis
Familial amyloidosis
Wild-type (senile) amyloidosis
Cardiac amyloidosis
Beta-2 microglobulin related amyloidosis
Gelsolin related amyloidosis
Lysozyme amyloid related amyloidosis
Leucocyte cell-derived chemotaxin 2 related amyloidosis
Fibrinogen A alpha-chain associated amyloidosis

Pathophysiology

Causes

Differentiating Amyloidosis from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

X-ray

Echocardiography and Ultrasound

CT scan

MRI

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:

Overview

Historical Perspective

In 1639, Nicolaus Fontanus autopsied a young man who had ascites, jaundice, liver abscess, and splenomegaly and his report has been the first description of amyloidosis. There is no significant data regarding the historical perspective of amyloidosis throughout the 18th century. Rudolph Virchow and Weber are the prominent figures with substantial work on amyloidosis during the 19th century. In 1922, Bennhold introduced Congo Red staining of amyloid that remains the gold standard for diagnosis.

Classification

Amyloidosis may be classified on the basis of type of amyloidogenic protein and associated clinical syndromes into primary (AL) amyloidosis, secondary (AA) amyloidosis, familial (AF) amyloidosis, transthyretin (ATTRwt) amyloidosis and dialysis-associated (AH) amyloidosis. It can also be classified based on extent of organ system involvement

Pathophysiology

Amyloid is an abnormal insoluble extracellular protein that deposits in the different tissues and causes organic dysfunction and a wide variety of clinical syndromes. In systemic amyloidosis, amyloid gradually accumulate and amyloid deposition is widespread in the viscera, blood vessel walls, and in the different connective tissues. Primary (AL) amyloidosis) is the most common type of amyloidosis. It results from aggregation and deposition of monoclonal immunoglobulin (Ig) light chains that usually produced by plasma cell clones. Secondary amyloidosis is associated with chronic inflammation (such as tuberculosis or rheumatoid arthritis). Hereditary (or familial) amyloidosis are autosomal dominant diseases that inherited variant proteins cause the production and deposition of amyloid fibrils. Some neurodegenerative disorderssuch as Parkinson's disease, Alzheimer, and Huntington's disease may occur in localised amyloidosis. On microscopic pathology, typical green birefringence under polarized light after Congo red staining (appears in red under normal light)

Causes

Hereditary amyloidosis can be caused by genetic mutations in different genes. Causes of acquired amyloidosis can include tuberculosis, familial Mediterranean fever, rheumatoid arthritis, multiple myeloma, ankylosing spondylitis, and psoriatic arthritis.

Differentiating Amyloidosis from other Diseases

Amyloidosis needs to be differentiated from acute myocarditis, bronchiectasis, multiple myeloma and other systemic diseases .

Epidemiology and Demographics

The incidence of amyloidosis is approximately 1.2 per 100,000 individuals per year worldwide. The prevalence of AL amyloidosis increased significantly between 2007 and 2015, from 1.6 per 100,000 in 2007 to 4.0 per 100,000 in 2015. The mortality rate of systemic amyloidosis is approximately 100 per 100,000 deaths in developed countries. In amyloidosis, the mean age of presentation is 55 - 60 years. Men are more commonly affected by amyloidosis than women.

Risk Factors

There are no established risk factors for amyloidosis. Some inflammatory conditions might increase the likelihood of amyloid deposition in the body.

Screening

There is insufficient evidence to recommend routine screening for amyloidosis.

Natural History, Complications and Prognosis

In amyloidosis, insoluble fibrils of amyloid are deposited in organs, causing organ dysfunction and eventually death. Patients with amyloidosis may eventually suffer from heart failure, nephrotic syndrome, hepatomegaly and peripheral neuropathy. In primary amyloidosis, the survival rate depends upon the type of organ involvement and the hematological response to treatment. In AL amyloidosis, untreated individuals have the worst prognosis. In this group of patients, the median survival is one to two years.

Diagnosis

Diagnostic Study of Choice

The diagnostic study of choice in amyloidosis is tissue biopsy of the affected organ. Congo Red staining will show apple green birefringence of the tissue sample under polarized light, and subtyping of light chains(for light chain amyloidosis) can be done via mass spectrometry. Bone marrow biopsy and organ-specific laboratory measurements are also important ancillary tests.

History and Symptoms

In amyloidosis, the range of symptoms depends on specific tissues and organs involved. Symptoms can be quite diverse.

Physical Examination

Common findings in amyloidosis include petechiae, ecchymosis, parotid gland enlargement, increased intraocular pressure, enlarged tongue, hepatomegaly, carpal tunnel syndrome, and Raynaud's phenomenon.

Laboratory Findings

Laboratory findings in amyloidosis include elevated erythrocyte sedimentation rate, increased BUN level, serum creatinine, protein, casts, or fat bodies in urine. Serum troponin, B-type natriuretic peptide, and beta-2-microglobulin are prognostic markers for heart failure. Amyloid deposits can be identified histologically by Congo red staining and viewing under polarized light where amyloid deposits produce a distinctive 'apple green birefringence'. Alternatively, thioflavin T stain may be used. An abdominal fat pad aspiration, rectal mucosa biopsy, or bone marrow biopsy can help confirm the diagnosis. They reveal positive findings in 80% patients.

Electrocardiogram

Electrocardiogram is particularly useful for cardiac amyloidosis. Findings on electrocardiogram include low voltage QRS complexes, left and right ventricular hypertrophy, left atrial abnormalities, pathological Q waves, and AV block.

Chest X-Ray

Chest x-ray findings in a case of amyloidosis include a coin lesion.

CT Scan

CT scan can be done to assess for amyloid deposition in particular organs. It can also be done to rule out other causes of organ dysfunction. However, MRI is more sensitive than CT in the diagnosis of amyloidosis.

MRI

MRI is commonly done to assess for amyloid deposition in particular organs. It can also be done to rule out other causes of organ dysfunction. A cardiac MRI is used when an echocardiogram fails to differentiate amyloidosis from hypertrophic cardiomyopathy.

Echocardiography

Echocardiography is critical in the diagnosis of cardiac amyloidosis. Echocardiogram should be done at diagnosis and routinely thereafter to monitor response to therapy.

Other Imaging Findings

Tissue doppler echocardiography and myocardial strain rate imaging has been shown to be very sensitive for the assessment of myocardial dysfunction in restrictive cardiomyopathy. The developmend of serum amyloid P component (SAP) scans has given physicians the ability to specifically locate amyloid deposits.

Other Diagnostic Studies

A tissue biopsy or fat aspirate should be done to confirm the presence or type of amyloid protein which is involved in the pathogenesis of the disease.

Treatment

There is no treatment for primary amyloidosis. The initial target in the treatment of this disorder is to correct the organ failure, as the disease is discovered at an advanced stage.

Medical Therapy

There are few available treatments for primary amyloidosis. Since the disease is typically discovered at an advanced stage, the initial treatment is aimed at preventing further organ damage and correcting the effects of organ failure. The most commonly used regimen for AL amyloidosis is CyBorD, which consists of cyclophosphamide, bortezomib, and dexamethasone.

Surgery

Organ-specific transplant may need to be done, depending on the organ involved. However, surgery is not commonly done in patients with amyloidosis, since it is usually a systemic disease that requires treatment of the underlying cause.

Prevention

Primary Prevention

There is no role for primary prevention in amyloidosis.

Secondary Prevention

There is no role for secondary prevention in amyloidosis.

References

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