Occult Varicella

Background: Localized varicella has been associated with UV-exposure
and skin trauma. Varicella restricted to a pre-existent dermatitis is
exceptional.
Objectives: The clinical features, cytohistologic and immunohistochemical
results, as well as serologic data of 6 patients with a sudden eruption of
vesicular and eroded lesions restricted to a pre-existent dermatitis are
presented.
Results: All patients (mean age: 8,3 years, range: 3–22) showed crops of
a few to numerous vesicular lesions clustered on the restricted sites of
posttraumatic wound, perianal streptococcal dermatitis, dermatomycosis,
allergic contact dermatitis, lichen sclerosus, and atopic foot dermatitis. All
the Tzanck smears and 1 biopsy revealed multinucleated giant cells,
consistent with herpes simplex virus (HSV) or varicella zoster virus (VZV)
infection. Immunohistochemistry using specific anti-VZV antibodies (IE63
and gE) was positive on all the smears and the biopsy, whereas HSV-I and
HSV-II immunolabeling was negative. VZV specific IgM , IgG EIAbased
serology, and positive VZV-specific IgM complement fixation test
suggested primary VZV infection. None had received varicella vaccine.
None of the patients presented a history of varicella nor experienced
breakthrough varicella. It was decided not to administer antiviral treatment,
as the varicella lesions remained localized without any further skin extension
and systemic signs. About 2 months later, EIA-serology revealed
positive VZV-IgG and negative IgM levels in 5/5 patients.
Conclusion: Some patients have varicella infection that remains hidden in
a pre-existent infectious and/or inflammatory dermatitis without ever
presenting full-blown chickenpox. The sudden occurrence of vesicular
and/or ulcerated lesions on a pre-existent dermatitis should prompt searching
for a viral infection.