| mediastinal space | <anatomy> The space in the thoracic cavity behind the sternum and in between the two pleural sacs (containing the lungs). (27 Sep 1997) |
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| mediastinal surface of lung | The part of the medial surface of a lung in contact with the mediastinum. Synonym: pars mediastinalis pulmonis, facies mediastinalis pulmonis, mediastinal part of lung. (05 Mar 2000) |
| mediastinal veins | Several small veins from the mediastinum emptying into the brachiocephalic veins or the superior vena cava. Synonym: venae mediastinales. (05 Mar 2000) |
| middle mediastinal mass | <radiology> Mnemonic: not VD, 90% malignant, Nodes, tumour (metastasis, lymphoma/leukaemia), infection, inhalational disease, Castleman disease, Tumour, primary lung, trachea, oesophagus carcinoma, Vascular, aneurysm, haematoma, Duplication cyst, bronchogenic, enteric, neurenteric (12 Dec 1998) |
| posterior mediastinal arteries | Numerous small arteries supplying the pleura and lymph nodes of the posterior mediastinum. Synonym: rami mediastinales aortae thoracicae, posterior mediastinal arteries. (05 Mar 2000) |
| posterior mediastinal lymph nodes | Nodes located along the thoracic aorta; they receive vessels from the oesophagus, diaphragm, liver and pericardium and send efferents to the thoracic duct and bronchomediastinal lymphatic trunk(s). Synonym: nodi lymphatici mediastinales posteriores. (05 Mar 2000) |
| posterior mediastinal mass | <radiology> Mnemonic: HALOVEEN, haematoma, abscess, lymph nodexs, osteophyte, vertebral (metastasis, plasmacytoma), extramedullary haematopoesis, oesophagus, neurogenic (12 Dec 1998) |
| adrenal cyst | <radiology> Same characteristics as renal cysts, but less common, thick wall, septations, calcifications suggests pseudocyst (12 Dec 1998) |
| adventitious cyst | 1. An accumulation of fluid in a cystlike loculus, but without an epithelial or other membranous lining. Synonym: adventitious cyst, false cyst. 2. A cyst whose wall is formed by a host cell and not by a parasite. 3. A mass of 50 or more Toxoplasma bradyzoites, found within a host cell, frequently in the brain; formerly called a pseudocyst, but now considered a true cyst enclosed in its own membrane within the host cell that may rupture to release particles that form new cysts, and apparently is infective to another vertebrate host. See: bradyzoite. Origin: pseudo-+ G. Kystis, bladder (05 Mar 2000) |
| allantoic cyst | Cyst occurring in a persistent portion of the urachus, presenting as an extraperitoneal mass in the umbilical region. It is characterised by abdominal pain, and fever if infected. It may rupture, leading to peritonitis, or it may drain through the umbilicus. (12 Dec 1998) |
| alveolar hydatid cyst | A hydatid cyst of a multiloculate type, usually in the liver, caused by Echinococcus multilocularis, adults of which are in foxes; larvae (alveolar hydatid) are found chiefly in microtine rodents, but also among humans such as trappers and others handling pelts of infected foxes and other carnivores; growth is by exogenous budding and is not limited by an outer laminated membrane as in the hydatid cyst from E. Granulosus; necrosis, cavitation, contiguous spread, and death usually ensue. Synonym: multilocular hydatid cyst, multiloculate hydatid cyst. (05 Mar 2000) |
| aneurysmal bone cyst | <radiology> ABC, 10 - 30 yrs, 75% before skeletal maturity, sites: long bones; also, flat bones Findings: metaphyseal if unfused, metaepiphyseal after fusion, lytic, expansile, thin, continuous rim, thin internal bony strands (12 Dec 1998) |
| angioblastic cyst | Mesenchymal tissue capable of forming blood in the embryo. (05 Mar 2000) |
| apical periodontal cyst | An inflammatory odontogenic cyst derived histogenetically from Malassez' epithelial rests surrounding the root apex of a nonvital tooth. Synonym: periapical cyst, radicular cyst, root end cyst. (05 Mar 2000) |
| apoplectic cyst | A pseudocyst formed of extravasated blood as in a stroke. (05 Mar 2000) |