Immunofluorescence findings in a reactivating lichenoid photoallergic chronic dermatitis (actinic reticuloid).

Background: Chronic photosensitivity dermatitis (CPD) (also named actinic reticuloid) is an unusual disease classically referred often in elderly men. Affected patients have severely itchy, thickened dry skin in areas exposed to the sun throughout the years.

Method: A Caucasian female patient who worked most of her life outside who had "chronic dermatitis" in her neck started planting chrysanthemum in her garden on a sunny day. Later, she presented edema, erythema, papules, and a few vesicles in her neck with severe pruritus.

Studies: A skin biopsy revealed the diagnosis of CPD, along with positive testing for ultraviolet B (UVB), minimal erythema doses (MED) for UVB (MEDB) UVA (MEDA) and PhotoPath.

Results: Direct immunofluorescence (DIF) stains using anti-human antibodies against fibrinogen, albumin, IgG, IgM, lambda, kappa, and C3c and C1q were positive at the base membrane area of the dermal epidermal junction, in the papillary dermis, as well as the neurovascular bundles in all the dermis and the extracellular matrix, especially those under the blisters.

Conclusion: With this case, we suggest not forgetting the importance of using DIF in reactivated CPD cases in addition to the photo patch testing.