Perichondritis  is inflammation of the perichondrium, a layer of connective tissue which surrounds cartilage. A common form, auricular perichondritis (perichondritis auriculae) involves infection of the pinna due to infection of traumatic or surgical wound or the spread of inflammation into depth (e.g. Infected transcartilaginous ear piercings). It may lead to severe deformation of the pinna if not treated vigorously with IV antibiotics. The causative organism is usually Pseudomonas aeruginosa. A rare form is laryngeal perichondritis (perichondritis laryngis). It develops suddenly due to an injury, virulent organisms or compromised immune status of the host, and also affects cartilage of the larynx. This may result in deformations and stenoses. Signs and symptoms
Signs of perichondritis or  chondritis  in  patients  with  an  embedded  earring  are  similar (these include pain, swelling and erythema of the overlying skin) and fluctuant swelling indicate an abscess that we should drain (typically associated with chondritis). Clinically, perichondritis can be differentiated from cellulitis of the pinna, in that the first usually does not involve the earlobe.In serious cases pus appears between the perichondrium and cartilage. Purulent melting of auricular cartilage takes place. Dead tissue tears away, as a result, auricle deforms strongly and becomes shrunken. See also
Chondritis

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The Mg2+ cation being the second most abundant cation in seawater and in rocksalt, the potential release of magnesium ions dissolving in brines intruding the deep geological repository is also expected to minimize the geochemical perturbations. MgO has an important place as a commercial plant fertilizer  and as animal feed. An aerosolized solution of MgO is used in library science and collections management for the deacidification of at-risk paper items. In this process, the alkalinity of MgO (and similar compounds) neutralizes the relatively high acidity characteristic of low-quality paper, thus slowing the rate of deterioration. MgO is also used as a protective coating in plasma displays. Magnesium oxide is used as an oxide barrier in spin-tunneling devices. Owing to the crystalline structure of its thin films, which can be deposited by magnetron sputtering, for example, it shows characteristics superior to those of the commonly used amorphous Al2O3. In particular, spin polarization of about 85% has been achieved with MgO versus 40–60 % with aluminium oxide. The value of tunnel magnetoresistance is also significantly higher for MgO (600% at room temperature and 1,100 % at 4.2 K) than Al2O3 (ca. 70% at room temperature). Precautions
Inhalation of magnesium oxide fumes can cause metal fume fever. See also
Calcium oxide
Barium oxide
Magnesium sulfide
Reactive magnesia

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References
External links
Data page at UCL
Ceramic data page at NIST
NIOSH Pocket Guide to Chemical Hazards at CDC