Identifying Lentigo Maligna Often Requires a Multidisciplinary Approach

The surgery can also be controversial, he said. The National Institutes of Health and many cancer organizations recommend 5 mm margins for the excision of lentigo maligna. However, in various trials 6 mm excisions-depending upon stage-resulted in successful surgery in up to 75% of cases. Mohs surgeons, Dr. Shockley said, perform the excision with 8 mm to 13 mm margins.

He said his recommendation for surgery is the standard excision with the expectation of flap reconstructive surgery.

‘Wonder Drug’ Imiquimod

For patients with a more frequent type of lesion, actinic keratosis, Dr. Shockley said the new wonder drug is the topical 5% imiquimod cream (Aldara). He said that imiquimod upregulates the innate and acquired immune system through stimulation of toll-like receptors; it increases the synthesis and release of cytokine such as interferon-alpha, interleukins, and tumor necrosis factor-alpha. In turn, this activity activates natural killer cells, macrophages, and Langerhans cells, resulting in antiviral and antitumor activity.

The problem with lentigo maligna is that if it is not treated properly, there is a high probability that it can recur-and it could recur as malignant melanoma.

In addition to actinic keratosis, the cream has been Food and Drug Administration approved for superficial basal cell carcinoma and external and peri-anal warts. Dr. Shockley said that imiquimod has also been used by doctors as a treatment for lentigo maligna, with varying degrees of success. He noted that such use is off-label.

The patient opens a packet of the expensive cream-12 packets costs $170-and rubs the cream, containing 50 mg of imiquimod, into the lesion. Eight hours later the cream is washed off. The treatment’s side effects are mainly related to the site of administration with erythema, irritation, itching, burning, and tenderness being the major adverse events. The use of the cream may also cause bleeding and infection at the site. Dr. Shockley said systemic symptoms such as fatigue, fever, and malaise are rare occurrences.

Patients who use this product report being moderately miserable, he said. The more reactions you get, the more likely you will get a cure.

Clinical Evidence

Dr. Shockley reviewed two clinical trials involving imiquimod. In one, imiquimod cleared actinic keratosis in 45% of patients compared to 3% of those using a vehicle cream. In that study, 436 patients used either placebo or imiquimod twice a week for 16 weeks. The overall reduction of lesions was 83% (J Am Acad Dermatol. 2004; 50: 714-721).