11 Ziemssen's Cyclop., xvii. p. 258.
12 Loc. cit.
13 Brit. and Foreign Med.-Chir. Review, Oct., 1865.
14 L'Union Méd., 5, 6, 7, 1880.
DIAGNOSIS.—The affection bearing the closest resemblance to spontaneous purpura is scurvy; indeed, its supposed relationship to this disease has given purpura one of its synonyms, land scurvy. The two affections, however, are probably without the slightest relationship. They possess in common the hemorrhagic symptoms, both in the tissues and from free surfaces, but the resemblance does not extend much beyond this. Scurvy depends upon deprivation of fresh vegetable food and the use of unsuitable and insufficient food generally, and upon bad hygienic surroundings. Purpura may—frequently does—appear in broken-down constitutions, but it equally attacks the strong and vigorous, while the character of food exerts no special influence on its production. Scurvy only follows long-continued privations and as a culmination of a train of distressing symptoms. Purpura appears in the midst of health, or after brief premonition, or during convalescence from totally unrelated diseases. In scurvy there is a decided tendency toward ulceration, which is absent in purpura. In scurvy the mouth and gums inflame and ulcerate, the latter becoming swollen, spongy, and of a bluish-red color. In purpura, ulceration of the buccal mucous membrane does not occur, and the gums are pale and intact. The curative influence of fresh vegetables, lime-juice, etc. in the treatment of scurvy is not observed in purpura. It has been claimed that purpura is but a mild degree of scurvy: this cannot be so, for we may have a mild scurvy or a severe, even fatal, purpura.
The hemorrhagic diathesis, or hæmophilia, presents points of analogy with purpura. Here, however, is found the almost constant history of heredity and the implication only of persons of the male sex. The disposition to bleed at all times upon the receipt of the smallest injury is quite unlike the suddenly-developed and transitory hemorrhages of purpura, which are also more generally distributed.
With the secondary hemorrhagic effusions and ecchymoses that occur in conditions of profound alterations of the blood and blood-vessels in cases of malignant small-pox, scarlatina, typhus fever, etc., and in some cases of poisoning, as from phosphorus, spontaneous purpura presents identities, but the history of the complaint and the condition of the patient will prevent error. A knowledge of the circumstances will serve to distinguish purpura simplex from the petechiæ and small ecchymoses produced by fleas, by diminished atmospheric pressure, by coughing, in the course of Bright's disease, etc.
Purpura rheumatica presents, as has been shown, many points of resemblance to erythema multiforme and erythema nodosum. The mild fever, the joint-pains, the extravasations of the latter affections, are much like the symptoms of this form of purpura. The nodular, inflamed, tender condition of the lesions, their location—frequently upon the extensor surfaces of the extremities—their course and duration, usually serve to identify erythema nodosum, while with erythema multiforme it is usually not difficult to observe its essentially inflammatory character. Scheby-Buch has shown the difficulties often opposed to the differentiation of purpuric lesions and ecchymoses due to violence.15 Where the petechial eruption of purpura simplex is well marked, where the internal hemorrhages of purpura hæmorrhagica are copious, the inquiries of the observer will usually lead him to correct conclusions. Where the ecchymoses are larger and upon exposed parts of the body, the diagnosis from the lesions alone becomes impossible, and due consideration of all concomitant circumstances is essential. It should be remembered that in purpura very slight violence may call forth extensive ecchymosis. This circumstance has important medico-legal bearings.
15 Viertelj. f. Dermatol. und Syph., 1879, p. 99.
PROGNOSIS.—Purpura usually terminates favorably. Its course runs from two to six weeks, rarely longer. Relapses and remissions are frequent. Purpura simplex is of very little gravity, and need excite little apprehension. Purpura rheumatica almost always ends in recovery; fatal terminations, however, have been known. Purpura hæmorrhagica is of much more serious import. Even here, however, though the patient may fall into profound debility from loss of blood, recovery is the rule, the symptoms gradually diminishing in severity until health becomes re-established. In fatal cases death ensues after prolonged and profuse losses of blood. Purpura may subside after a single outbreak or many relapses, and recrudescences may occur extending through months. Anæmia may persist long after the disappearance of purpuric symptoms. A tendency to purpura may be shown at irregular intervals for years, and even throughout life.