Hydroa Vacciniforme Workup

Updated: Jun 14, 2021
  • Author: Gregory Toy, MD; Chief Editor: Dirk M Elston, MD  more...
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Laboratory Studies

Consider the following laboratory studies:

  • Complete blood cell count to investigate constitutional symptoms
  • Measurement of EBV DNA; best detected with whole blood rather than serum or plasma: EBV DNA in peripheral blood mononuclear cells (PBMCs) provides a diagnostic indicator of hydroa vacciniform (HV) [29]
  • Cell free EBV DNA in plasma, as it may be related to serious complications like hemophagocytic lymphohistiocytosis [29]
  • Viral culture of blister fluid to rule out herpes virus infection
  • Erythrocyte sedimentation rate and antinuclear antibody, anti-Ro, and anti-La antibody tests to rule out bullous lupus erythematosus
  • Plasma or serum porphyrin assay to exclude cutaneous porphyrias
  • DNA repair studies to rule out xeroderma pigmentosum

Imaging Studies

Imaging studies are not routinely obtained as part of the workup of hydroa vacciniforme (HV).


Other Tests

Repetitive, broad-spectrum, UV-A phototesting may be warranted. Repetitive, broad-spectrum, low-dose UV-A irradiation can elicit lesions clinically and histologically identical to those produced by natural UV exposure, although results are inconsistent. The minimal erythemal dose of UV-B and UV-A in these patients is reduced. [30]


Histologic Findings

Early lesions reveal an epidermal, multilocular vesicle with reticular degeneration and demonstrate EBV RNA (EBER positive) in lymphocytes. [31]  A dense, perivascular, lymphohistiocytic infiltrate with vessel hemorrhage may occur in the dermis. Late lesions show epidermal and dermal necrosis with a surrounding, chronic, inflammatory infiltrate. Direct immunofluorescence study results are usually normal, except for rare reports (2 patients) of C3 deposits at the dermoepidermal junction and in the small dermal vessels.