MADRID — Mohs surgery for lentigo maligna and lentigo maligna melanoma yields a substantially lower recurrence rate and smaller surgical deficit than does conventional surgery, according to Dr. Leonard H. Goldberg.
"It's especially useful on cosmetically sensitive areas of the body like the eyelids, where a 5-mm or 1-cm or 2-cm margin is virtually impossible because you'd destroy the patient's cosmetic appearance," Dr. Goldberg said at the 13th World Congress on Cancers of the Skin.
Of 708 cases of lentigo maligna and lentigo maligna melanoma that he treated using Mohs surgery from 1997 through 2007, the recurrence rate was 1.3%.
In contrast, conventional surgery is associated with recurrence rates of 8%-20%, he said. That's because the clinical margins of lentigo maligna are often indistinct, being masked by actinic keratoses or other sun-induced dysplastic changes.
The lentigines are "often much larger than what you'd expect," he said. "There's always the problem of where does the lentigo maligna end? Are those single cells in the periphery also lentigo maligna?"
Dr. Goldberg utilizes Dr. Helmut Breuninger's "Tübingen torte" technique of surgical specimen cutting using 90-degree sectioning, along with immunostaining. En-face (parallel) control of the entire surgical margin is considerably more reliable than bread-loafed cross-sectioning of the excised melanoma specimen.
"Bread-loafing doesn't always find the tumor. We don't bread-loaf tumors anymore," he said.
The change in practice came as a result of a study that Dr. Goldberg and his colleagues conducted in 36 patients with melanoma in situ treated with Mohs surgery with positive margins after initial excision with 5-mm margins (Dermatol. Surg. 2007;33:1434-9).
Because the average linear extent of melanoma at the surgical margin was 1.4 mm, they calculated that bread-loafing at 1-, 4-, and 10-mm intervals would have a 58%, 19%, and 7% chance, respectively, of detecting positive margins. To detect positive margins with 100% certainty, the bread-loafing would have to be done at 0.1-mm intervals, which is impractical, he said.
Dr. Goldberg noted that his personal 1.3% recurrence rate is in the same ballpark as outcomes reported by other Mohs surgeons. For example, researchers reported a 0.3% recurrence rate in 331 patients with melanoma in situ or lentigo maligna, compared with a 20% rate in 81 historical controls who underwent conventional surgery (J. Am. Acad. Dermatol. 2005;52:92-100).
In a separate review of four other published studies totaling 546 patients with lentigo maligna and lentigo maligna melanoma with margin control by various modifications of Mohs surgery, recurrence rates were 0.5%-2.8% (J. Am. Acad. Dermatol. 2007;57:659-64).
Dr. Goldberg reported no financial conflicts.