Mediastinum Health Dictionary

Investigation of the mediastinum by means of an endoscope inserted through an incision in the neck. Mediastinoscopy is used mainly to perform a biopsy of a lymph node. The sample is removed by tiny blades on the endoscope.... mediastinoscopy

A malignant tumour of the LYMPH NODES divided histologically and clinically into two types: Hodgkin’s disease, and non-Hodgkin’s lymphoma. Hodgkin’s disease or lymphadenoma was named after Thomas Hodgkin (1798–1866), a Guy’s Hospital pathologist, who ?rst described the condition.

Hodgkin’s disease The incidence is around four new cases per 100,000 population annually, with slightly more men than women contracting it. The ?rst incidence peak is in age group 20–35 and the second in age group 50–

70. The cause of Hodgkin’s is not known, although it is more common in patients from small families and well-educated backgrounds. The disease is three times more likely to occur in people who have had glandular fever (see MONONUCLEOSIS) but no link with the EPSTEIN BARR VIRUS has been established (see Burkitt’s lymphoma, below)

The disease is characterised histologically by the presence of large malignant lymphoid cells (Reed-Sternberg cells) in the lymph glands.

Clinically the lymph glands are enlarged, rubbery but painless; usually those in the neck or just above the CLAVICLE are affected. Spread is to adjacent lymph glands and in young people a mass of enlarged glands may develop in the MEDIASTINUM. The SPLEEN is affected in about one-third of patients with the disorder. Treatment is either with RADIOTHERAPY, CHEMOTHERAPY or both, depending on when the disease is diagnosed and the nature of the abnormal lymph cells. Cure rates are good, especially if the lymphoma is diagnosed early.

Non-Hodgkin’s lymphoma (NHL) This varies in its malignancy depending on the nature and activity of the abnormal lymph cells. The disease is hard to classify histologically, so various classi?cation systems have been evolved. High- and low-grade categories are recognised according to the rate of proliferation of abnormal lymph cells. No single causative factor has been identi?ed, although viral and bacterial infections have been linked to NHL, and genetic and immunological factors may be implicated. The incidence is higher than that of Hodgkin’s disease, at 12 new cases per 100,000 population a year, and the median age of diagnosis is 65–70 years. Suppression of the immune system that ocurs in people with HIV infection has been linked with a marked rise in the incidence of non-Hodgkin’s lymphoma and Hodgkin’s disease.

Most patients have painless swelling of one or more groups of lymph nodes in the neck or groin, and the liver and spleen may enlarge. As other organs can also be affected, patients may present with a wide range of symptoms, including fever, itching and weight loss. If NHL occurs in a single group of lymph nodes, radiotherapy is the treatment of choice; more extensive in?ltration of glands will require chemotherapy – and sometimes both types of treatment will be necessary. If these treatments fail, BONE MARROW TRANSPLANT may be carried out. Prognosis is good for low-grade NHL (75 per cent of patients survive ?ve years or more); in more severe types the survival rate is 40–50 per cent for two years.

Another variety of lymphoma is found in children in Africa, sometimes called after Burkitt, the Irish surgeon who ?rst identi?ed it. Burkitt’s lymphoma is a rapidly growing malignant tumour occurring in varying sites, and the Epstein Barr virus has a role in its origin and growth. A non-African variety of Burkitt’s lymphoma is now also recognised. CYTOTOXIC drug therapy is e?ective.... lymphoma

(germinoma, gonocytoma) n. a malignant tumour of the ovary, thought to arise from primitive germ cells; it is homologous to the *seminoma of the testis. About 15% of such tumours affect both ovaries; outside the ovary they have been recorded in the anterior mediastinum and in the pineal gland. Dysgerminomas may occur from infancy to old age, but the average age of patients is about 20 years. Treatment is by oophorectomy, with chemotherapy for residual disease.... dysgerminoma

n. air in the tissues. In pulmonary emphysema the air sacs (*alveoli) of the lungs are enlarged and damaged, which reduces the surface area for the exchange of oxygen and carbon dioxide. Severe emphysema causes breathlessness, which is made worse by infections. There is no specific treatment, and the patient may become dependent on oxygen. The mechanism by which emphysema develops is not understood, although it is known to be particularly common in men in Britain and is associated with chronic bronchitis, smoking, and advancing age. See also chronic obstructive pulmonary disease.

In surgical emphysema air may escape into the tissues of the chest and neck from leaks in the lungs or oesophagus; occasionally air escapes into other tissues during surgery, and bacteria may form gas in soft tissues. The presence of gas or air gives the affected tissues a characteristic crackling feeling to the touch, and it may be visible on X-rays. When air moves to the mediastinum the condition is known as *pneumomediastinum. It is easily absorbed once the leak or production is stopped.... emphysema

n. inflammation of the midline partition of the chest cavity (mediastinum), usually complicating a rupture of the oesophagus (gullet). Sclerosing mediastinitis often leads to *fibrosis, which may cause compression of other structures in the thorax, such as the superior vena cava, the bronchial tree, or the oesophagus.... mediastinitis

n. air in the mediastinum visible on chest X-ray. It can be a complication of surgical *emphysema due to pneumothorax, but the air can originate from the upper airways or the upper gastrointestinal tract. A rare cause is gas-forming organisms. See Hamman’s sign.... pneumomediastinum