Formic acid burn--local and systemic effects. Report of a case

Formic acid is an organic acid which has mainly been used in industry, but in recent years its use in agriculture has greatly increased in the Scandinavian countries. Formic acid is more caustic to the skin than acetic acid. However, reports on formic acid burns are scarce in the medical literature, and no serious burn has previously been described. A few reports on formic acid ingestion have been published. It is of great interest that formic acid has been shown to play the major role in the methanol poisoning syndrome. A case of severe burn with undiluted formic acid is reported. In the beginning, the dermal injury seemed to be of minor degree, but then the patient, a 15-year-old girl, developed signs of systemic formic acid intoxication, including metabolic acidosis, intravascular hemolysis and hemoglobinuria. These signs were similar to those described as a result of formic acid ingestion. The systemic effects were successfully treated without late sequelae, but the burn turned out mainly to be full-thickness, resulting in major scarring, as commonly seen after various chemical burns.