Amyloidosis

Amyloidosis is an extracellular deposit mainly in the walls of blood vessels and basement membranes and along reticulin fibers. It resembles hyaline by light microscopy (homogenous esenophilic and refractive on staining with haematoxylin and eosine) but can be differentiated from it by special stains (Congo red).

Structure of amyloid: is formed of 90% fibril protein (many different types) and 10% glycoprotein called P-component. Despite the different types of amyloid present they all appear the same on biopsy.

Types of amyloidosis

Generalized (systemic) amyloidosis

  1. 1ry amyloidosis (B-cell dyscrasia): AL type of amyloid protein resulting from fibril formation by monoclonal antibody light chains e.g. multiple myeloma.
  2. 2ry amyloidosis (reactive systemic amyloidosis): systemic amyloidosis of the AA type.
  3. Haemodyalisis associated amyloidosis: 70% of patients undergoing haemodialysis due to deposition of B2 microglobulin which is not normally filtered by the membrane.
  4. Hereditary amyloidosis: several types which may be localized or generalized.

Localized amyloidosis

  1. Senile amyloidosis of the heart and choroid plexus.
  2. Within endocrine tumors.
  3. Idiopathic localized amyloid deposits.

Clinical manifestations

It can present with many varying manifestations according to the site of involvement. However, when it affects the kidney it leads to nephrotic syndrome.

Treatment

  • No curative treatment for amyloidosis is available.
  • Peripheral stem cell transplantation, melphalan and prednisone are all under study and may be beneficial in some cases.

Conservative treatment for nephrotic syndrome

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