Mediastinal (thymic) large B cell lymphoma

Mediastinal large B cell lymphoma is a type of non-Hodgkin's lymphoma. Lymphoma is cancer of the lymphatic system and can be subdivided into Hodgkin's and non-Hodgkin's lymphoma.Lymphatic system is an important part of our immune system that helps fight infection. It is composed of various organs e.g. lymph nodes, thymus (in the mediastinum - behind the breastbone), spleen and bone marrow. These are connected by a network of tiny lymphatic vessels. Lymph is a colourless fluid that circulates in the lymphatic system. It contains lymphocytes, which are white blood cells that fight infection. There are 2 types of lymphocytes: B cells and T cells. Mediastinal large B cell lymphoma is a cancer of B cells.Mediastinum is between the breast bone and the back bone. It is the space in the chest that contains all the organs of the chest (heart, oesophagus, trachea, thymus and some large vessels) except the lungs and pleurae (the layer covering the lungs). Mediastinal large B cell lymphoma arises from the thymus (a lymphatic organ in the lymphatic system) in the mediastinum. Mediastinal large B cell lymphoma makes up about 2-6% of all lymphomas.The majority of patients are very young - around 30 years when they are diagnosed.It is slightly more common in females than in males - this is opposite of other types of non-Hodgkin's lymphoma. The cause is unknown. It does not run in families or occur because of genetic changes. There does not seem to be a relation to toxic agents.It is non-infectious and cannot be passed on to other people. This is a tumour that grows very quickly and causes symptoms in the chest as described below. It is usually localised (confined to an area) when patients come to the doctor.It requires prompt treatment. If the disease comes back, it has often spread to other organs such as the liver, kidneys or brain. Blood will be drawn and sent to the laboratory to look at certain features: The number and nature of blood cells Liver function Kidney function Level of other substances in the blood e.g. lactate dehydrogenase (LDH) and beta-2 microglobulin (indicates poorer disease outcome if the levels are high) Level of proteins (e.g. alpha-fetoprotein and beta-HCG) to differentiate mediastinal large B cell lymphoma from another disease called mediastinal germ cell tumour that happens in males. Alpha-fetoprotein and beta-HCG will be raised in mediastinal germ cell tumour. Of all patients, 40-80% are cured with treatment.If the disease comes back after treatment, it normally happens in the first year after diagnosis. A patient who is disease-free for 2 years after initial diagnosis is likely to be cured.Patients who do not show good response to initial treatment or whose disease comes back may require intensive chemotherapy with tranplantation of bone marrow cells. About 30% of this group will eventually stay free of the disease. The usual treatment is chemotherapy. The most commonly used combinations of drugs are the CHOP regimen and MACOP-B regimen. Treatment may last from 3-6 months.Most patient respond well to initial therapy. Response is assessed by performing scans.However, in some patients, the disease comes back in about one year. These patients may require intensive chemotherapy with transplantation of bone marrow cells.Steroids are usually given together with chemotherapy to help reduce feelings of sickness. Side effects from chemotherapy include nausea, vomiting, hair loss, infection and fever. Nausea and vomiting can be relieved by drugs.After the chemotherapy, radiotherapy is sometimes given to the mediastinal area.