Rare case of metformin-induced leukocytoclastic vasculitis

To report a case of leukocytoclastic vasculitis (LV) related to metformin.

A 33-year-old woman developed palpable purpura on her lower limbs after starting self-medication with metformin 850 mg/day for weight loss. Drug-induced vasculitis was suspected, metformin was stopped, and the rash improved significantly. One month later, the woman again took metformin. Similar cutaneous lesions recurred, and skin biopsy showed LV, which was managed by discontinuing metformin and applying topical antiseptics. The patient had no further episodes of skin rash over a follow-up period of 3 months.

Metformin has widespread use throughout the world. It has a variety of metabolic and vascular effects. Our patient developed a rash within a few days of metformin administration. Resolution of skin manifestations within several days after withdrawal of the drug and their recurrence when the drug was reintroduced were consistent with a pathogenic role of metformin. Other known causes of vasculitis were excluded in a reasonable way. According to the Naranjo probability scale, the vasculitis experienced by our patient was probably due to metformin.

Clinicians should be aware of the ability of metformin to induce cutaneous LV.