The histopathology is distinctive and demonstrates intraepidermal reticular degeneration, and cellular necrosis.
Most cases remit spontaneously by late adolescence.
Etiology of hydroa vacciniforme is not known. Skin lesions occur on sun-exposed skin, such as the face, ears, and hands, and may be accompanied by a mild keratoconjunctivitis, photophobia, and constitutional symptoms. In Scotland, for example, the reported prevalence is 0.34 cases per 100,000 people. No mortality is associated with typical hydroa vacciniforme. Females have a higher incidence of HV than males and report earlier onset.