The Amyloidosis Of Spleen And Diagnosis Treatment Notes

Amyloidosis Of Spleen

Amyloid deposition in the spleen, for some unknown reasons, may have one of the following two patterns :

1. Sago Spleen Grossly:

Splenic enlargement is not marked and the cut surface shows characteristic translucent pale and waxy nodules resembling sago grains hence the name.

• Microscopically: The amyloid deposits begin in the walls of the arterioles of the white pulp and may subsequently extend out and replace the follicles.

2. Lardaceous Spleen:

• Grossly: There is generally moderate to marked splenomegaly (weight up to 1 kg). The cut surface of the spleen shows map-like areas of amyloid (lardaceous lard-like; lard means fat of pigs).
• Microscopically: The deposits involve the red pulp in the walls of splenic sinuses and the small arteries and in the connective tissue.
  Confirmation is by observing Coprophilia in Congo red staining and demonstration of apple-green birefringence under polarizing microscopy in the corresponding positive areas.

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Amyloidosis Of The Liver

In about half the cases of systemic amyloidosis, the liver is involved in amyloidosis.

• Grossly: The liver is often enlarged, pale, waxy, and firm.
• Histologically: The features are as under Later, as the deposits increase, they compress the cords of hepatocytes. Eventually, the liver cells are shrunken and atrophic and replaced by amyloid. However, the hepatic function remains normal even at an advanced stage of the disease. To a lesser extent, portal tracts, and Kupffer cells are involved in amyloidosis.

Amyloidosis Of Heart

The heart is involved in systemic amyloidosis quite commonly, more so in the primary than in secondary systemic amyloidosis. It may also be involved in a localized form of amyloidosis (senile cardiac).

• In advanced cases, there may be pressure atrophy of the myocardial fibers and impaired ventricular function which may produce restrictive cardiomyopathy.
• Amyloidosis of the heart may produce arrhythmias due to deposition in the conduction system.

• Grossly: The heart may be enlarged. The external surface is pale, translucent, and waxy. The epicardium, endocardium, and valves show tiny nodular deposits or raised plaques of amyloid.
• Microscopically: The changes are as under: In cases of primary amyloidosis of the heart, the deposits are seen around the myocardial fibers in the interstitium in ring-like formations (ring fibers)
  • In the localized form of amyloid of the heart, the deposits are seen in the left atrium and the interatrial septum.
  • Besides, amyloid deposits may be seen in the blood vessels and the cardiac valves.

Amyloidosis Of Alimentary Tract

Involvement of the gastrointestinal tract by amyloidosis may occur at any level from the oral cavity to the anus. Rectal and gingival biopsies are the common sites for diagnosis of systemic amyloidosis.

The deposits are initially located around the small blood vessels but later may involve adjacent layers of the bowel wall. The tongue may be the site for tumour-forming amyloid, producing macroglossia.

Other Organs:

The deposits of amyloid may also occur in various other tissues such as the pituitary, thyroid, adrenals, skin, lymph nodes, respiratory tract, and peripheral and autonomic nerves.

Diagnosis And Prognosis Of Amyloidosis Diagnosis

Amyloidosis may be detected as an unsuspected morphological finding in a case, or the changes may be severe to produce symptoms and may even cause death.

The diagnosis of amyloid disease can be made from the following investigations:

1. Tissue Diagnosis:

Routine examination of a biopsy or fine needle aspiration, followed by Congo red staining and examination under polarizing microscopy, are the two confirmatory methods of tissue diagnosis of amyloidosis:

• Histologic examination: Histologic examination of biopsy material is the commonest and confirmatory method for diagnosis in a suspected case of amyloidosis.
  • Biopsy of an affected organ is likely to offer the best results for example, Kidney biopsy in a case of dialysis, and sural nerve biopsy in familial polyneuropathy.
  • In systemic amyloidosis, renal biopsy provides the best detection rate, but rectal biopsy also has a good pick-up rate. However, gingival and skin biopsy have poor results.
• Fine needle aspiration or biopsy: Fine needle aspiration or biopsy of abdominal subcutaneous fat followed by Congo red staining and polarising microscopic examination for confirmation has become an acceptable simple and useful technique with excellent results.

2. In Vivo Congo Red Test:

A known quantity of Congo red dye may be injected intravenously in living patients. If amyloidosis is present, the dye gets bound to amyloid deposits and its levels in the blood rapidly decline. The test is, however, not popular due to the risk of anaphylaxis to the injected dye.

3. Other Tests:

Besides tissue diagnosis, a few other tests that are supportive but not confirmatory of amyloidosis include protein electrophoresis, immunoelectrophoresis of urine and serum, and bone marrow aspiration.

Prognosis

Amyloidosis may be an incidental finding at autopsy, or in symptomatic cases diagnosis can be made from the methods already described. The prognosis of patients with generalized amyloidosis is generally poor:

• Primary systemic amyloidosis: If left untreated, is rapidly progressive with a mean survival of 2 years after diagnosis. Therapy in these cases is directed at reducing the clonal marrow plasma cells as is done for treatment of multiple myeloma.
• Secondary reactive amyloidosis: However, has a somewhat better outcome due to controllable underlying condition. It responds and improves with control of chronic infections, autoimmune diseases, etc.

Renal failure and cardiac arrhythmias are the most common causes of death in most cases of systemic amyloidosis. Newer targeted therapies are being developed to interrupt the protein misfolding and inhibit fibril aggregation.

Amyloid Stains, Morphology, Diagnosis, Prognosis:

Amyloid deposition causes morphologies and functional disturbance of the affected organ. The affected organ is enlarged, waxy, and translucent.

• Confirmation of amyloid in tissue is done by special stains, most commonly Congo red staining (pink-red color) followed by its examination under a polarising microscope (apple-green birefringence).
• Kidneys may be involved in all forms of systemic amyloidosis; renal failure is a leading cause of death in amyloidosis.
• Amyloids in the spleen may appear as sago or lardaceous deposits. Other organs that may be involved in amyloidosis are the heart, liver, bowel, endocrine organs, skin, etc.
• The gold standard for making a diagnosis of amyloid is by tissue demonstration of amyloid deposit (by biopsy or aspiration cytology).

Primary systemic amyloidosis is rapidly progressive with a poor prognosis. Secondary or reactive amyloidosis can occur at any age (including children) and has a better outlook by control of the underlying chronic infection or autoimmune disease.