D3.379 - Varenicline´s DRESS Syndrome

Tobacco addiction represents a significant public health concern, adversely affecting both quality of life and life expectancy. Consequently, a range of pharmacological interventions have been developed to support smoking cessation, as it is varenicline.

A 61-year-old woman, went under treatment with Varenicline for 18 days, after which she started with an itchy diffuse skin rash that affected both the face and groin and armpits, scalp and both palms in its progression.She presented three lymph nodes in different locations. Because the rash continued to expand, despite the withdrawal of the possible culprit drug, reaching 65-70% of the body surface area, and so did the blood levels of eosinophils, she was admitted into hospital regime, where she received 2 mg per kilo of methylprednisolone, with an excellent result. She did not have fever or internal organ affection. During evolution, the Regiscar score reached 3 points. The skin biopsy showed findings consistent with toxicoderma. A peripheral blood smear ruled out the presence of atypical lymphocytes.Similarly, viral serology was performed, which ruled out reactivation of HSV-6 and 7, CMV and EBV, as well as hepatotropic viruses.And because the DRESS Syndrome is a late onset cutaneous adverse reaction, included in the SCARs (severe cutaneous skin reactions) affections regarding drugs, it was tested out after 5 months of the reaction with an epicutaneous test for varenicline at 10% petrolatum and 20% petrolatum.A positive lymphocyte transformation test (LTT) with varenicline was also performed on the patient 4 months after the rash.

The clinical suspicion, Regiscar Score and complementary tests, helped confirming a case of DRESS syndrome induced by varenicline, that yielded positive in the epicutaneous test after 96 hours at 0.1 mg/ml concentration and negative at 0.05 mg/ml one. Varenicline was also positive in the TTL, that was negative in two healthy control patients, which further validates its result.

TThis case documents DRESS Syndrome as a new possible late cutaneous hypersensitivity reaction to varenicline, not recorded previously and resumes the approach of a suspected DRESS Syndrome case, where epicutaneous testing and LTT might make a difference in the diagnosis.