Overview of amyloidosis
Amyloidosis is a disease of varying degrees of dysfunction of tissues and organs caused by the deposition of amyloid (a specific protein similar to starch that turns blue when exposed to iodine, mainly a polyglycoprotein complex, which is a homogeneous, amorphous, eosinophilic substance under light microscopy and a specific apple-green fluorescent light under a Congo red-stained polarized-light microscope) in the extracellular mesenchyme (ECM) of different tissues and in the walls of blood vessels. It mainly involves the heart, kidney, liver, spleen, gastrointestinal tract, muscles, nerves, skin and other tissues and organs. Liver amyloidosis is a part of systemic amyloidosis, which is caused by the deposition of proteins of different structures in the extracellular mesenchyme of different tissues and in the walls of blood vessels. The incidence is low and the age of onset is high, reportedly averaging 64 years, with a male predominance.
Etiology
The etiology of primary hepatic amyloidosis is unclear, and it is partly secondary to rheumatoid arthritis, osteomyelitis, tuberculosis and lymphoma. In a few patients, the disease is associated with family genetics.
Symptoms
Hepatic amyloidosis is part of systemic amyloidosis with other amyloid manifestations. The most common symptoms are fatigue, weakness, weight loss, upright hypotension, shortness of breath after activity, and edema, which are nonspecific. Some of the symptoms are related to the involved organs, such as carpal tunnel syndrome, nephrotic syndrome, congestive heart failure, arrhythmia, gastrointestinal bleeding, chronic diarrhea, malabsorption, hepatosplenomegaly, cough, dyspnea, and megatongue sign.
The liver may be normal in size on palpation or mildly or moderately enlarged. The texture is firm on palpation. Spontaneous hepatic rupture may also occur, resulting in the formation of a subpericardial hematoma or hemoperitoneum.
Examination
1. Liver puncture biopsy
It is the most reliable diagnostic method. Staining of liver tissue sections can be done with Congo red and amethyst. Always observe under a polarized light microscope. Liver puncture carries the risk of inducing hemorrhage, and skin and rectal biopsy are safer choices. The presence of multiple myeloma should also be noted, and myelography should be performed if necessary.
2. Hematological and coagulation tests
Prolonged prothrombin time, while partial thromboplastin time and prothrombin time are mostly normal.
3. Imaging examination
Hepatomegaly is seen on radionuclide liver scan, CT and MRI, and poor reflux map-like changes similar to Bugart’s syndrome can be seen on enhancement scans due to amyloid deposition in the perisinusoidal space.
Diagnosis
The diagnosis of amyloidosis should be established before considering the presence of hepatic amyloidosis. Amyloid can be deposited in a variety of organs in the body, and the clinical presentation is highly variable, making the diagnosis difficult. The possibility of the disease should be considered whenever there is multisystem involvement such as congestive heart failure, arrhythmia, intractable diarrhea, and hepatosplenomegaly, especially when occurring in men over 40 years of age. If hepatomegaly and mildly abnormal liver function are found in patients with multiple myeloma, chronic inflammatory diseases, and chronic suppurative infections, one should be alert to the possibility of combined hepatic amyloidosis.
Differential diagnosis
Hepatosplenomegaly needs to be differentiated from various liver diseases causing hepatomegaly, such as acute hepatitis, cirrhosis due to various causes, primary or secondary hepatocellular carcinoma, hepatomegaly, as well as acute or chronic infectious diseases or other blood diseases.
Treatment
Primary hepatic amyloidosis of uncertain etiology can be treated with colchicine, which can effectively reduce proteinuria and improve renal function. A melphalan (phenylalanine azelnidazole) prednisone (MP) regimen may also be used. Since hydrocarbons are ineffective in non-immunoglobulin amyloidosis, the diagnosis of primary amyloidosis must be established before starting treatment. Hepatic amyloidosis secondary to osteomyelitis, tuberculosis, lymphoma, and rheumatoid arthritis is treated for the primary cause.