State the etiology of purpura.
In most instances no cause can be assigned. The disease occurs at all ages from childhood to advanced life, and in individuals, apparently, in good and bad health alike. The hemorrhagic type is oftener seen in subjects debilitated or in a depraved state of health. A microörganism is also looked upon as a factor by some observers, especially in the grave type of disease.
State the diagnostic characters of purpura.
The appearance, irregularly or in crops, of bright-red or purplish spots, evidently of hemorrhagic nature, and not disappearing upon pressure, and as they are fading, going through the several changes of color usually observed in any ecchymosis.
How does scurvy (scorbutus) differ from purpura?
Scurvy, which may resemble the severe grade of purpura, has a different history, a recognizable cause, usually a peculiar distribution, and is accompanied with general weakness and a spongy, soft and bleeding condition of the gums.
What is the pathology of purpura?
The lesion of purpura consists essentially of a hemorrhage into the cutaneous tissues. The blood is subsequently absorbed, the hæmatin undergoing changes of color from a red to greenish and pale yellow, and finally fading away.
State the prognosis
The milder varieties disappear in the course of several weeks or months, and are rarely of serious import; the outcome of purpura hæmorrhagica is somewhat uncertain; although usually favorable, a fatal result from internal hemorrhage is possible. The variety known as Schönlein's disease is alarming, but seldom fatal. Henoch's disease is, however, always of grave import.