Fixed food eruption caused by cashew nut.

BACKGROUND: The diagnosis of fixed 'drug' eruption is not difficult for dermatologists, but it is difficult to identify the causative agent when the patient denies ingestion of any drugs. There have been some reported cases of fixed 'food' eruption.

CASE SUMMARY: A 71-year-old woman experienced repeated erythema and tense bulla with a burning sensation and pruritus on the right ankle. The eruption remitted leaving pigmentation. The patient denied previous ingestion of any drug. We suspected cashew nut as the causative agent. Oral challenge and patch tests with cashew nut were positive.

DISCUSSION: A fixed eruption without any antecedent drug ingestion should alert us to think of food as a causative agent.