Biología, Botánica, Genética y Zoología
What is Hepatitis ?
epatitis is an inflammation of the liver. The word comes from a combination of two Greek words: "Hepatos-" ("liver"), and "-itis" ("inflammation"). The inflammation of the liver (hepatitis) can be caused by several factors:
- viruses - viral hepatitis is caused by several viruses that attack mainly the liver. The viruses identified until now have been named as A, B, C, D, E, and G, from which A and E are contagious.
- toxic agents - alcohol, drugs or other chemicals.
- auto-immune disorders.
If inflammation and necrosis of hepatocytes persist for more than 6 months we are dealing with chronic hepatitis.
Based on histological criteria, chronic hepatitis classification is as follows:
chronic lobular and
chronic active hepatitis.
A) Chronic Persistent Hepatitis and
Chronic Lobular Hepatitis
They usually follow acute hepatitis B or C. These disorders may persist for years, but are mild and rarely progress to chronic active hepatitis or cirrhosis.
Clinical features for both are :
Liver biopsy shows:
Treatment is not necessary and natural recovery is usual. However, periodic controls are recommended.
B) Chronic Active Hepatitis
It's a serious disorder that has a general tendency to progress to hepatic cirrhosis and possibly even primary liver cancer.
Histologically it's characterized by:
- Initially a lymphocytic portal reaction is present and lymphocytes infiltrate progressively the acini, causing considerable necrosis of hepatocytes (spotty and confluent necrosis).
Necrosis of hepatocytes causes collapse of the reticular strome that supports liver cells. Then an irreversible deposition of collagen (fibrosis) occurs. Zones of collapse, fibrosis and abnormal hepatocellular regeneration (nodular regeneration) lead to distortion of the acinar architecture, which is characteristic for liver cirrhosis.
The histological activity of Chronic Active Hepatitis is a concept that takes into account both inflammatory infiltration and hepatocellular damage that lead to fibrosis. Inflammatory activity defines grade (mild, moderate or severe) of Chronic Active Hepatitis, and therefore its prognosis (probability of evolution into cirrhosis), and is to a great extent reversible with therapy.
The degrees of fibrosis express the stage reached by Chronic Active Hepatitis into its evolution to cirrhosis. It is irreversible, but therapy, reducing inflammation, can lessen or stop its progression.
Patients are usually asymptomatic for a long time. Signs and symptoms often occur when an advanced histological disease is present. Sometimes symptoms are vague and may be mistaken for other disease or simply consequences of aging.
The main symptoms are:
Clinical signs are:
Other organs affected
In about 20% of cases other organs are affected:
Chronic Hepatitis B
Hepatitis B Virus (HBV) infection becomes chronic in about 10% of cases. In the natural evolution of chronic hepatitis B can be distinguished three phases:
Non Replicative Infection