Mediastinum

Pathophysiology

Acute mediastinitis is an infection that develops within the mediastinum itself. This infection (caused by bacteria ) can be serious and most often complicates chest surgery or a traumatic or spontaneous rupture of the esophagus, for example, following a perforation due to esophageal cancer or retching with the glottis closed. Treatment of acute mediastinitis requires irrigation and drainage , as well as surgical repair of any esophageal injury if necessary. Antibiotic therapy tailored to the causative organisms is also essential. Delay in diagnosing this condition and in initiating treatment can lead to the patient's death.

Pneumomediastinum is characterized by the presence of gas in the mediastinal spaces, particularly between fat and connective tissue cells (a type of protein that provides support to tissues in general). Sometimes artificially induced, it allows for the study, using X- rays , of the organs contained within the mediastinum ( artificial pneumomediastinum of Coury and Mathé, or gaseous mediastinography ).

Chronic mediastinitis corresponds to the development of sclerosis , that is, a loss of elasticity, in the protective membranes of the organs contained within the mediastinum, particularly the blood vessels , esophagus , and nerves . This leads to voice changes due to paralysis of the left vocal cord and paralysis of the diaphragm . The infection most often responsible is tuberculosis . Sometimes, no etiology (cause) is found. Some patients also present with retroperitoneal fibrosis . Familial forms are also observed, likely related to an autoimmune mechanism (the patient produces antibodies against their own tissues).

During the multicentric reticulohistiocytosis (in English: multicentric reticulohistiocytosis), also called lipoid dermato-arthritis, is a condition affecting young adults, and characterized by inflammation of the joints, causing mutilations, and mainly affecting the fingers. It is characterized, among other things, by the presence of lumps in the skin and on the mucous membranes (layer of cells covering the inside of hollow organs, in contact with the air). In some patients, localizations are observed in the lungs, within pleura or in the mediastinum. In multicentric reticulohistiocytosis, the patient presents with impairment of the general condition, with hyperthermia (fever), increased volume of ganglia (adenopathies), and muscle inflammation (myositis). Microscopic examination shows that the tissues are invaded (infiltrated) with a variety of white blood cells, the histiocytic, which contain vacuoles (small lakes) of fat, and sometimes, large (giant) cells. This condition is one of the overload reticuloendotheliosis.

Kussmaul's paradoxical pulse is observed in certain mediastinitis or pericarditis (inflammation of the pericardium : the membranes covering and protecting the heart) accompanied by fluid secretion and constriction (decrease in cardiac volume). Kussmaul's paradoxical pulse occurs when there is an obstruction preventing air from entering the lungs, such as in cases of laryngeal pathology ( stenosis ).

Chronic fibrositic mediastinitis of drug origin is most often caused by long-term treatment with Desernil , a medication used to treat migraines. This type of fibrosis typically resolves, more or less completely, after discontinuation of the drug.

Aortitis is an inflammation of the aorta , sometimes detected by auscultation, which reveals a murmur (known to specialists as a continuous superior vena cava murmur ). This continuous murmur is very loud and has a late systolic accentuation . It is located next to the sternum (it is said to be parasternal) at the level of the 2nd and 3rd right intercostal spaces. Furthermore, it radiates primarily towards the right axilla. This continuous murmur is also observed in patients with mediastinitis . Some cardiologists believe it is due to compression of the superior vena cava.

Aberrant goiter is a type of goiter that develops at the expense of an accessory thyroid gland . It is sometimes located in the mediastinum, but also on the sides of the neck or at the base of the tongue.

Hemomediastinum refers to a blood effusion, localized in the cellular tissue of the mediastinum.

Merkel cell hiberna is a rare, benign tumor located under the skin, primarily in the armpits and scapular region (around the neck). This type of tumor is composed of brown lipid (fat) tissue, distinct from normal adipose tissue, and comparable to the superior mediastinal fat of certain hibernating animals. Some consider it a type of liposarcoma made up of cells containing lipids similar to those found in hibernating animals.

Sternberg's leukosarcomatosis is a malignant condition characterized by the presence of lymph node tumors primarily located in the mediastinum. Patients also present with a blood disorder resembling acute lymphoblastic leukemia , associated with numerous metastases.

Löfgren's syndrome appears with sarcoidosis, associating it with erythema nodosum ( a skin condition with redness and nodules):

• Joint damage.
• The ganglia of particular shape at the thoracic level.
• The adenopathies of fever.
• The arthralgia (pain in the joints).