Onkológia 6/2016

Systemic amyloidosis

Amyloidosis is a rare disease, characterized by deposits of low-soluble proteins – amyloids – inside tissue, with the result of damage to its function. The most common type of systemic amyloidosis is the AL amyloidosis, which may also be classified as a monoclonal gammopathy. It is caused by deposits of free-flowing immunoglobulin light chains. We may also find AA amyloidosis, caused by deposits of serum amyloid A often accompanying chronic inflammatory diseases, senile amyloidosis caused by deposits of non-mutated transthyretin (wTTR), or hereditary amyloidosis with the most common subtype of ATTR amyloidosis caused by deposits of mutated transthyretin. Organs most commonly affected by this disease are the heart, kidneys, nervous system and liver, but also soft tissues, gastrointestinal tract, or lungs. Damage to the heart, in the form of concentric hypertrophy, is the most significant factor in predicting the prognosis of the patient. Diagnosis of amyloidosis is based upon proof of amyloid presence in the tissue, the typing of the amyloid, and therefore discerning the type of amyloidosis and evaluation of organ damage. The proof of amyloids and its typing may be done through non-targeted biopsy (most often from subdermal fat tissue in the abdominal area, salivary glands, or rectal mucosa), or from a targeted biopsy of the affected organ. In the process of amyloidosis typing, it is always necessary to include tests for the most common type, the AL amyloidosis, therefore to look for presence of monoclonal immunoglobulin and its light chains. If we suspect AL amyloidosis, we always include a bone marrow test. To assess organ damage, it is important to check cardiac function using an echocardiography examination, to investigate kidney function and proteinuria. Treatment of amyloidosis is dependent on its type. In AA amyloidosis, it is the treatment of the base disease, in some types of hereditary amyloidosis we may do a liver transplant, in senile amyloidosis treatment using doxycycline, and in AL amyloidosis, it is the combination of anti-cancer therapy, including autologous transplant of blood producing cells. Because of high rarity of these diseases, the diagnosis and treatment of amyloidosis should be forwarded to specialized centers.

Keywords: systemic amyloidosis, AL amyloidosis, monoclonal gammopathy, concentric cardiac hypertrophy, proteinuria