Facial eruptions
A 78-year-old woman presented to her physician with complaints of facial pain 2 weeks into a 3-week prescribed 5-fluorouracil (5-FU) field treatment for facial actinic keratoses (AKs). The patient had a previous medical history of multiple nonmelanoma skin cancers and AKs. Upon examination, the physician noted marked erythema and some crusting over widespread areas of previous AKs.
What’s your diagnosis?
This was a vigorous response to the 5-FU treatment and was actually within the range of expected outcomes for a patient with a heavy burden of AKs. The erythema and superficial skin flaking spared areas unaffected by pre-cancers.
AKs manifest as rough, pink to brown macules or papules on sun-damaged skin and represent a precancerous change in keratinocytes that can lead to invasive squamous cell carcinoma. For this reason, AKs are often treated when they are observed. When targeting an entire “field” of AKs, a gold standard therapy is topical 5-FU. Prescribing 5-FU is safe and effective, but requires patient education, therapy customization, and anticipatory guidance.
Compared with other field treatments (eg, photodynamic therapy, topical diclofenac, imiquimod), 5-FU is the most successful and cost effective; it is first-line therapy and has the longest track record.1,2 5-FU represses DNA synthesis. It’s helpful to describe 5-FU to patients as “fake DNA” that targets precancerous cells that are dividing rapidly. But a word of caution: Patients should be advised, in advance, to avoid significant sun exposure while using 5-FU, as the drug will lose its targeted effect and cause more generalized skin damage.
Physicians can modulate the severity of the response to 5-FU by decreasing the frequency or length of therapy by using a weaker (and more expensive) once daily 0.5% long-acting formulation. Additionally, to improve comfort, low-potency topical steroids such as hydrocortisone ointment 0.5% to 2.5% can be applied after completion of therapy to speed up the healing process. These adjustments improve tolerance of therapy, but the precise effect on efficacy is unknown.
Because of the degree of redness and erythema that developed in this patient, treatment was stopped a week early. There was also concern about possible bacterial involvement in the heavy skin sloughing, so the patient was given topical mupirocin ointment to apply TID for 7 days. Her skin cleared after 3 weeks and all previous AKs were clinically eliminated.
Text courtesy of Jonathan Karnes, MD, medical director, MDFMR Dermatology Services, Augusta, ME. Photos courtesy of Jonathan Karnes, MD (copyright retained).