## HYDROA VACCINIFORME

**Synonyms:** Hydroa puerporum; Hydroa aestivale; Recurrent summer eruption.

Hydroa vacciniforme is a recurring vesicular eruption upon the exposed portions of the skin, excited by extremes of temperature, and which, upon its disappearance, leaves scars. The lesions appear as numerous, isolated or grouped, small red macules upon which rapidly develop tense, round, pin head to pea sized vesicles. Their contents, at first clear, later become turbid or puriform. Areolae may or may not be present. The vesicles dry within a few days and form thick, yellowish or brownish, closely adherent crusts. Not infrequently some of the drying vesicles become depressed and crust first at the center, like a vaccine vesicle. The crusts fall off in about a week and leave red depressed scars that eventually become pale and practically indistinguishable from small pox pits. The most conspicuous deformity is usually the atrophic scarring of the ears and nose which successive attacks may cause. Crops of lesions continue to appear without any regularity as to time, usually at intervals of a few days or weeks, but sometimes in such rapid succession that the rash may be present continuously for six or eight weeks. The distribution of the lesions is symmetrical and they are limited usually to the face, ears, back of the neck, and backs of the hands and wrists. Most cases begin about the second or

third year of life and the disease usually decreases in intensity and disappears gradually within a few years after puberty. Cases have been known to develop after puberty, as late as the twenty-sixth year; most of these were in women. In the great majority of instances the disease occurs in boys. Heat is the most potent exciting factor and for that reason the attacks appear generally during the summer months, after exposure to the sun's rays. Artificial heat is capable of exciting an attack in some patients. In others the rash appears only in extremely cold weather, or after exposure to high winds. The cause of the disease seems to be an unusual vulnerability of the skin to irritation from exposure. Not infrequently outbreaks are preceded by some general symptoms as e. g., discomfort, anorexia, sleeplessness. The subjective symptoms may be a feeling of fullness and heat before the rash appears and slight itching afterwards. **DIAGNOSIS:** In appearance only, not in its distribution, course and age of onset, hydroa vacciniforme somewhat resembles *erythema bullosum* and *dermatitis herpetiformis*, but the lesions of these two diseases do not leave scars. **TREATMENT:** No known treatment is very satisfactory. Avoidance of the exciting cause is the only reliable measure. Arsenic and salicin are both recommended.

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