Patch testing with Indian standard series of 20 allergens in 125 patients of chronic dermatitis and dermatoses

Objectives: Patch testing is generally done in cases of allergic contact dermatitis to find the offending allergen/s. It has been less reported in patients clinically presenting as non-eczematous contact reactions such as lichen planus, lichenoid eruption, lichen planus pigmentosus and facial melanosis overlap. In addition, it may give clues to the sensitizers leading to chronic, recurring dermatitis and overlap of dermatoses in the form of systemic contact dermatitis. The aim of the present study was to identify the sensitizer/s with patch testing in patients presenting with non-eczematous contact reactions as well as chronic, relapsing dermatitis and overlap of dermatoses. Material and Methods: In the present study, patch testing was done using the Indian standard series in 125 cases presenting clinically as lichen planus, lichen planus pigmentosus, facial melanosis, cheilitis, mucosal lichen planus and vulvar dermatitis, in addition to cases of chronic and recurrent dermatitis such as nummular eczema, lichenoid eruption, pompholyx, photo aggravated dermatitis, air borne contact and hand and feet dermatitis. Results: The tests were positive in 102 (81.6%) patients, negative in 16, doubtful in 3 and invalid in 4 patients. Positive results were found in 100% cases of photo aggravated dermatitis and chronic dermatitis of hands/feet dermatitis and 76% cases of facial melanosis and lichen planus pigmentosus overlap, 88.9% cases of nummular eczema, 81.8% cases of lichenoid eruption, 75% cases of lichen planus, 57% cases of atopic eczema, 66.6% cases of pompholyx, and 100% of mucosal lichen planus. Test for nickel was positive in 40 (32%) cases, parthenium in 37 (29.6%), cobalt in 23 (18.4%), fragrance in 19 (15.2%), paraphenylenediamine in 17 (13.6%), paraben in 9 (7.2%) and neomycin in 5 (4%) cases, either alone or in combination. In the present study, in addition to eczematous dermatoses, non-eczematous conditions such as lichen planus, lichenoid eruption, lichen planus pigmentosus and facial melanosis also showed positive results on patch testing. Conclusion: Patch testing should be considered in patients presenting with chronic and recurrent dermatitis and overlap of more than one type of dermatoses. Identification and elimination of culprit allergens can help in achieving long term remission in these chronic conditions.