D3.84 - Delayed hypersensitivity to hydroxychloroquine with positive patch test

Hydroxychloroquine (HXQ) is an antimalarial drug with immunosuppressive effect used in different pathologies. Hyperpigmentation is the most common cutaneous adverse effect, but delayed hypersensitivity has been reported as a maculopapular exanthema (MPE), contact dermatitis (CD), photosensitivity, toxic epidermal necrolysis (TEN), acute generalized exanthematous pustulosis (AEGP) and drug reaction with eosinophilia and systemic symptoms (DRESS). 

67-year-old woman with rheumatoid arthritis referred by Rheumatology due to a reaction with HXQ. 20 days after starting HXQ treatment developed generalized and pruritic maculo-papular lesions. She discontinued HXQ and was treated with bilastine 20 mg p.o., methylprednisolone 80 mg and dexchlorpheniramine 10 mg both intravenous with no improvement. Deflazacort 30 mg and hydroxyzine 25 mg p.o. was associated for 1 week with complete resolution in a week. There were no scales, hyperpigmentation or mucosal involvement or systemic symptoms.

Analysis with complete blood count, kidney and liver function were requested. Path tests were performed with HXQ at 5% in water and 10% dimethyl sulfoxide (DMSO).

There were no alterations in the analysis. The patch test was only positive at 96 hours with 10% HXQ in DMSO (image 1.) The rest were negative.

We report a delayed MPE due to HXQ confirmed by patch test with DMSO 10%. Desensitization was proposed, but it was suspended due to Rheumatology. Despite the lack of standardization and low positivity in path tests with HXQ its use is recommended in cases of especially severe delayed reactions. Dilutions of HXQ 5% in water are suggested for photosensitivity and 10% DMSO in MPE and PEGA, coinciding with the positivity in our case.