Petechia.

Petechia. This term is given to spots of a dusky crimson or purple colour, quite flat, with a well-defined margin, and unaffected by pressure, which closely resemble flea-bites. These spots result from a minute extravasation of blood beneath the cuticle. They occur most frequently on the back, at the bend of the elbow, and in the groin. They indicate an altered state of the blood, and are characteristic of the disease called purpura; but are often symptoms of very serious diseases, as of typhus fever, plague, scurvy, &c. They likewise occur in very severe cases of smallpox, measles, and scarlet fever, when their presence must be regarded as indicative of extreme danger.