Hydroa vacciniforme (HV) is a rare photosensitivity that manifests as papulovesicles and scarring following ultraviolet A (UVA) exposure. Although the pathogenesis of HV is unknown, an association with Epstein-Barr virus (EBV) has been suggested. Investigators performed a detailed study to assess the involvement of EBV in seven adults with HV.

UVA radiation was administered to the skin of three of these patients with active HV for up to 5 consecutive days and produced the characteristic umbilicated papulovesicles. Biopsy specimens taken from the photo-induced lesions were found to have significantly more EBV-positive cells than adjacent normal skin, an observation that was confirmed by polymerase chain reaction (PCR) analysis. On electron microscopy, viral particles were observed in keratinocytes from the lesional skin but not in surrounding normal skin. Blood samples showed greater amounts of EBV DNA in the patients with active disease than in those in remission, but the difference did not achieve statistical significance. However, the HV patients did have significantly greater levels of EBV DNA than the 35 control patients with other photosensitivity diseases (P<0.001); only 1 such control patient had elevated levels of EBV DNA.

Comment: Epstein-Barr virus has been previously reported in HV patients, particularly in those with severe disease, many of whom developed natural killer/T-cell Epstein-Barr virus–associated lymphoma. This thorough experimental design and highly sensitive techniques in this study found further support for involvement of EBV in the pathogenesis of this enigmatic disease. It will be interesting to see if this association extends to children, in whom most cases of HV occur. In addition to providing insight into HV pathogenesis, these findings may also have practical significance: At times, it can be difficult to differentiate HV from other photosensitive dermatoses; EBV serology could help differentiate HV from erythropoietic protoporphyria, polymorphous light eruption, and actinic prurigo.

— Craig A. Elmets, MD

Published in Journal Watch Dermatology August 20, 2010