Hydroa vacciniforme and hydroa vacciniforme-like T-cell lymphoma: an uncommon event for transformation

Background: Hydroa vacciniforme (HV) is associated with Epstein-Barr virus (EBV) infection and a risk of transformation to lymphoma. Methods: We retrospectively analyzed six HV cases for EBV association and transformation to HV-like T-cell lymphoma. Clinicopathologic features were reviewed and cases were assessed for EBV-encoded RNA (EBER) by in situ hybridization, double staining with immunohistochemistry and EBER and for T-cell clonality. Results: The male-to-female ratio was 5:1, with a median age at diagnosis of 18.5 years. All patients initially had recurrent vesicles, necrotic ulcers or scars on sun-exposed areas. Symptoms were present before diagnosis between 2 weeks to 10 years. The mean follow-up time was 106.3 months. Four patients (67%) were EBV-positive. All four EBV-positive and one EBV-negative patients had relapsing clinical course. Double staining proved EBV infection in T-cells. Moreover, one EBV-positive patient developed HV-like T-cell lymphoma with hemophagocytosis after 209 months of recurrent papulovesicular eruptions and eventually died. T-cell clonality was successfully performed in four HV patients and all showed polyclonal results; the transformed HV-like T-cell lymphoma was monoclonal. Conclusions: In EBV endemic areas, HV is frequently (67%) associated with EBV infection, but transformation to HV-like T-cell lymphoma seems to be uncommon (17%) and bear a dismal outcome.