Cutaneous recall reactions with systemic fluorouracil

5-Fluorouracil is used extensively to treat actinic keratoses as there is selective excessive uptake of 5-fluorouracil in rapidly dividing cells, thus causing inflammation in lesional skin. We report 2 cases of inflammation occurring on clinically normal skin after fluorouracil had been administered parenterally for carcinoma of the oesophagogastric junction and lower third of the oesophagus, respectively. In the first case, actinic keratoses had previously been treated with topical fluorouracil and in the second case, although there were no previous actinic keratoses, there was a high degree of previous solar exposure of the affected areas. In each case, there was a good response to topical steroid application. No recurrence was experienced on further doses of systemic fluorouracil when the skin was treated prophylactically with topical steroids. Recognition of these reactions is important if unnecessary discontinuation of chemotherapeutic drugs is to be avoided as a result of fear of allergic drug reactions.