Prognosis

"This affection is not grave; it disappears of itself in four or five weeks. It is subject to recur."

Hydroa vacciforme is the same, only that the vesicles are varioliform.

Hydroa bulleux (pemphigus with little bullae) is an arthritic affection which is generally little known.

The eruption shows itself by bullae, which present one important character - the inequality of their size. Some are as large as a lentil; the largest do not go beyond the size of a pea. These bullae are rounded, arranged in an irregular manner, in groups of three or four; they are filled with transparent fluid, which grows thick quickly and takes a yellowish color; finally they are placed on a red surface, which extends from their base in the form of an areola. Whilst new bullae are developing, the old ones dry up and are replaced by a yellowish scab; and if one of these is rubbed off by scratching there appears a violet-colored, slightly excoriated surface. In the interval of the crops of bullae there is no morbid phenomenon observed except the ordinary well-marked itching. The patient preserves his appetite, and the nutrition is not at all altered. Bazin states that the course is chronic, that the disease appears in successive crops, and lasts generally from five to six months; that it is more frequent in men than in women, and appears in adults from twenty to forty years; that the seasons and variations of temperature have a marked influence on its development; that it is most common in the spring, and is excited by gout.