Amyloidosis is an extracellular deposition in various tissues of amyloid fibril proteins and of a protein called amyloid P component (AP); the identical component of AP is present in the serum and is called SAP. These amyloid deposits can affect normal body function. Acquired systemic amyloidosis (AL), known as primary amyloidosis, occurs in patients with B cell or plasma cell dyscrasias and multiple myeloma in whom fragments of monoclonal immunoglobulin light chains form amyloid fibrils. Secondary amyloidosis (AA) occurs in patients after chronic inflammatory disease, in whom the fibril protein is derived from the circulating acute-phase lipoprotein known as serum amyloid A. Clinical features of AL (primary amyloidosis) include a combination of macroglossia and cardiac, renal, hepatic, and GI involvement, as well as carpal tunnel syndrome and skin lesions. These occur in 30% of patients; and since they occur early in the disease, they are an important clue to the diagnosis. There are few or no characteristic skin lesions in AA (secondary amyloidosis), which usually affects the liver, spleen, kidneys and adrenals; but there is a certain degree of overlap, and some skin lesions occur. In addition, skin manifestations may also be associated with a number of (rare) heredofamilial syndromes.
Causes of Systemic Amyloidosis
The exact mechanism that causes secondary systemic amyloid is unknown. The risk factors include chronic inflammatory or infectious diseases. Secondary systemic amyloid occurs in association with multiple myeloma, and chronic conditions (those that last for 5 or more years) such as: rheumatoid arthritis, tuberculosis, long term paraplegia, bronchiectasis, cystic fibrosis, chronic osteomyelitis, recurrent pyogenic (involving pus) skin infection or abscess, decubitus ulcers, chronic renal dialysis, juvenile chronic arthritis, systemic lupus erythematosus, Reiter’s syndrome, ankylosing spondylitis, Hodgkin’s disease, Sjogren’s syndrome, and hairy cell leukemia.
Symptoms of Systemic Amyloidosis
- Fatigue
- Numbness of hands and feet
- Weak hand grip
- Weight loss
- Shortness of breath
- Swelling of the extremities
- Swallowing difficulties
- Irregular heart rhythm
- Bleeding in the skin
- Enlarged tongue
Diagnosis
The combination of purpuric skin lesions, waxy papules, macroglossia, carpal tunnel syndrome, and cardiac symptoms and signs. A tissue diagnosis can be made from the skin biopsy. Scintigraphy after injection of I-labeled SAP is now available for estimating the extent of the involvement and can serve as a guide for treatment.
Treatment
Cytotoxic drugs can modify the course of amyloidosis AL associated with multiple myeloma.
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