Hydroa

Hydroa is a term that can refer to several different dermatological conditions characterized by the eruption of vesicles or blisters, often associated with sun exposure. The most common form is Hydroa vacciniforme, a rare, chronic, and recurrent photosensitive disorder. It typically begins in childhood and is more prevalent in males. Hydroa vacciniforme presents with small, itchy bumps and blisters that appear on sun-exposed areas, particularly the face, ears, and backs of hands. These lesions can evolve into pustules and then crusts, often leading to small, pitted scars (vacciniform lesions) upon healing, hence the name.

The exact cause of Hydroa vacciniforme is not fully understood, but it is believed to be an abnormal reaction to ultraviolet (UV) radiation, specifically UVA and UVB wavelengths. Genetic factors may also play a role. While generally benign, in rare cases, severe or persistent Hydroa vacciniforme has been associated with systemic symptoms such as fever, malaise, and lymphadenopathy, and in extremely rare instances, has been linked to Epstein-Barr virus (EBV) infection and a more severe condition known as hydroa vacciniforme-like lymphoproliferative disorder.

Management of Hydroa vacciniforme primarily focuses on photoprotection, including limiting sun exposure, wearing protective clothing, and using broad-spectrum sunscreen. Antimalarial drugs like hydroxychloroquine and chloroquine have shown some efficacy in reducing the frequency and severity of outbreaks. Topical corticosteroids may be used for symptomatic relief of itching and inflammation. In cases associated with EBV, antiviral therapies might be considered. The prognosis is generally good, with most individuals experiencing improvement or resolution of symptoms as they reach adulthood.