AL (Primary) Amyloidosis
AL amyloidosis is the most commonly diagnosed form of amyloidosis. In this disorder, the body abnormally produces a piece of an antibody called a “light chain” which accumulates in amyloid fibrils in different organs.
The cells which produce the defective antibody light chains are all identical (also known as ‘clonal’), and for this reason, the disease is sometimes considered to be cancerous.
Indeed, AL amyloidosis is closely related to a type of bone marrow cancer called “myeloma” – another disease in which identical clones of antibody-producing cells proliferate.
The main difference between myeloma and AL amyloidosis is that in myeloma the primary injury to the body is from the proliferation of the abnormal cells, whereas in amyloidosis the primary injury to the body is from the accumulation of the light chains into amyloid deposits. Not surprisingly, there can be overlap between the two diseases, and patients are diagnosed with both AL amyloidosis and myeloma in approximately 10 percent of cases.
Injury from amyloid deposits can occur in any organ which amyloid infiltrates, and occurs as a consequence of disruption of the normal tissue architecture and by direct tissue injury. Common manifestations include the following:
Heart
Amyloid deposits originally impair the heart muscle’s ability to relax, and ultimately impair the heart muscle’s ability to squeeze.
In addition, amyloid deposits can cause abnormalities in the heart’s electrical system, causing the heart rate to be too fast or too slow.
Common signs and symptoms of amyloid cardiac involvement include fluid retention, fatigue, shortness of breath, dizziness, low blood pressure, and fainting.
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| Using this staining method from a heart biopsy sample, amyloid fibrils stain light pink. Note how the amyloid deposits are seen everywhere and encircle each heart cell. | Using this staining method from a heart biopsy sample, amyloid fibrils stain blue. Note how the amyloid deposits are seen everywhere and encircle each heart cell. |
Using this advanced imaging called "electron microscopy", amyloid deposits (labeled A) can be seen to infiltrate normal heart cells (labeled "H"). 
Heart ultrasound ("echocardiogram") from a normal patient and one with amyloid deposits in the heart. Note how much thicker the walls appear in the patient with amyloidosis. The thickness is not due to extra heart muscle, but rather from deposits of amyloid fibrils.
On ultrasound imaging (echocardiography), the heart muscle often appears thickened; the ‘thickening’ actually represents amyloid infiltration.
Cardiac complications represent the most common cause of death in patients with AL amyloidosis, and the presence and degree of cardiac involvement represents the biggest factor which determines prognosis.
Kidneys
Amyloid deposits most commonly lead to protein loss in the urine, and can ultimately lead to kidney failure.
Common signs of kidney involvement include fluid retention/edema (swelling of the ankles/legs).
Amyloid deposits are seen in the kidney of this patient. The entire filtering apparatus pictured here is inundated with amyloid deposits.
Nerves
Amyloid deposits in nerves can lead to numbness/tingling, pain, or (less commonly) weakness.
In addition, amyloid deposits in nerves can contribute to low blood pressure.
Bone Marrow
Bone marrow involvement in AL amyloidosis can occur either as a result of proliferation of the cells which produce the light chains (as is seen in myeloma) or by amyloid deposits themselves occurring in the bone marrow. Either of these scenarios can lead to low blood counts, including white blood cell count (raising susceptibility to infection), red blood cell count (leading to anemia and fatigue) or platelets (leading to increased bleeding susceptibility).
Gastrointestinal Tract/Tongue
The gastrointestinal tract is a frequent site of amyloid involvement. Amyloid deposits can occur in the tongue, leading to enlargement (called ‘macroglossia’).
Amyloid deposits in the lip and tongue are present in this patient. Note the "scalloped" appearance of the tongue in which indentations are present on both sides (arrows). This occurs because the enlarged tongue chronically presses against the upper teeth.
Deposits elsewhere in the gastrointestinal tract can lead to difficulty swallowing and/or constipation. Amyloid can deposit in the liver; while these most often do not cause symptoms, they can cause abnormalities in your liver function tests (often part of routine bloodwork).
Amyloid deposits are seen in the esophagus of a patient with amyloidosis. Amyloid involvement of the gastrointestinal tract can lead to symptoms including difficulty swallowing, constipation, and tongue enlargement.
Skin/soft tissue
In some individuals, amyloid accumulates in the skin and soft tissue. This can cause significant changes in appearance, particularly if amyloid deposits occur in the face.
Amyloid deposits in the wrist can lead (along with the deposits in nerves themselves) to carpal tunnel syndrome. Amyloid deposits in the blood vessels of the skin can make them more fragile, and lead to easy bruising.