Inflammation may be -

Acute when it arises rapidly, lasts a short time, and destroys tissue.

Chronic when arising slowly, lasting a long time, and giving rise to the formation of fibrous connective tissue.

Infectious when caused by some living organism.

Non-infectious when it does not arise from the action of a living organism. 7

Exudative if the inflammation is characterized by the presence of an exudate. According to the variety of the exudate, the inflammation may be as follows:

Serous when the exudate consists of a fluid having few cellular contents.

Fibrinous when particles of fibrin are present in the exudate.

Purulent when pus cells (leukocytes) are present in large numbers.

Hemorrhagic when erythrocytes escape in quantity.

Parenchymatous when the actively secreting cells of a glandular organ are involved.

Interstitial if the inflammatory process involves the connective-tissue framework of an organ.

Catarrhal when limited to mucous membranes.

In the early stage the secretion of mucus by the cells ceases, the surface becomes dry, and the blood-vessels congested. Later on, the secretion is increased in amount, frequently changed in character, and the congestion of the vessels somewhat lessened.

Desquamative if there is a casting off of epithelium in a catarrhal inflammation.

Vesicular when there are larger and smaller circumscribed elevated areas containing a serous exudate, as in blisters.

Pustular when the circumscribed elevations contain pus.

Diphtheric or croupous when there is a marked coagulation of fibrin on the surface with the formation of a pseudo-membrane in which are found degenerated cells of various types - epithelial, leukocytes, and erythrocytes.

In it there is usually necrosis involving the superficial epithelium, or going deeper and attacking the submucosa as well as the mucosa.

Ulcerative if accompanied by a loss of superficial substance.

Degenerative when the destruction of tissue is extensive.

Adhesive when, as the result of the presence of fibrin, replacement by fibrous tissue follows and the two opposing surfaces become more or less adherent, the process being the same as occurs in scar formation. It may go on to the point where the cavity entirely disappears, and is then called obliterative.

Gangrenous when there has been infection of the tissues by putrefying, saprophytic organisms and gangrene is present.

Phlegmonous when the interstitial tissues become infiltrated by pus.

Productive when the formation of fibrous connective tissue is prominent.

Specific when caused by a definite micro-organism.