Metformin Induced Lichenoïd Drug Eruption

Cutaneous lichenoid drug eruptions are rare adverse drug reactions reminiscent of lichen planus. The most frequently reported culprit drugs are Checkpoint inhibitors, tyrosine kinase inhibitors and TNF-α inhibitors, but other drugs can also be responsible. This case-report is about a 49-year-old woman with a history of type 2 diabetes. She started taking metformin 160 weeks before the onset of a pruritic lichenoid rash on the trunk and limbs, of which the histopathology was in favor of an adverse cutaneous lichenoid drug eruption caracterized by the presence of eosinophilic polynuclei in the perivascular infiltrate. The patient benefited from oral corticosteroids with discontinuation of metformin which resulted in the resumption of the lichenoid rash.