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1. A soft external structure that forms the boundary of the mouth or opening to the oral cavity.
SYN: SEE: labium oris
2. One of the lips of the pudendum (labia majora or minora).
SEE: labia; SEE: labium
3. A liplike structure forming the border of an opening or groove.

Chancre: It is not unusual to have the initial lesion of syphilis appear on the lip of the mouth as an indurated base with a thin secretion and accompanied by enlargement of the submaxillary glands. Condyloma latum: This appears as a mucous patch, flattened, coated with gray exudate, with strictly delimited area, usually at the angle of the mouth. Eczema: This is characterized by dry fissures, often covered with a crust, bleeding easily, and occurring on both lips. Epithelioma: This may be confused with chancre. It seldom appears before the age of 40, but there are exceptions. It may appear as a common cold sore, a painless fissure, or other break of the lower lip. A crust or scab covers the lesion, leaving a raw surface if removed. Pain does not appear until the lesion is well advanced. It is much more common on the lower lip than on the upper. Herpes: These lesions may appear on the lips in pneumonia, typhoid, common cold, and other febrile diseases. Tuberculous ulcer: This type of ulcer is located at the inner portion of the lip, close to the angle of the mouth. Pathological examination is necessary for verification.

Examination is considered to be incomplete unless the lips are everted to expose buccal surfaces. Bluish or purplish: This sign may appear in the aged, in those exposed to great cold, and in hypoxemia. Dry: Mouth dryness may be seen in fevers or be caused by drugs such as atropine, by thirst, or by mouth breathing. Fissured: This may occur after exposure to cold, in avitaminosis, and in children with congenital syphilis. Pale: Pallor may be seen in anemia and wasting diseases, in prolonged fever, and after a hemorrhage. Rashes: These may be manifestations of typhoid fever, meningitis, or pneumonia. Mucous patches may appear in secondary syphilis, chancre, cancer, and epithelioma.

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