'Slow Mohs' advised for lentigo maligna
EXPERT ANALYSIS FROM SDEF HAWAII DERMATOLOGY SEMINAR
MAUI, HAWAII – "Slow Mohs" has gained near-universal acceptance among skin cancer specialists as a definitive surgical technique for complete removal of lentigo maligna melanoma while simultaneously sparing normal tissue, according to Dr. Ellen Marmur of Mount Sinai School of Medicine, New York.
The big advantage that slow Mohs has over standard wide local excision with 0.5- to 1-cm margins is a 5-year cure rate approaching 100%. In contrast, standard excision has a recurrence rate of up to 20%, she said at the Hawaii Dermatology Seminar, sponsored by Global Academy for Medical Education/Skin Disease Education Foundation.
Bruce C. Jancin/IMNG Medical Media
Slow Mohs is a modified form of Mohs micrographic surgery. The surgery compares with conventional Mohs: It is staged, margin-controlled excision. But in slow Mohs, rush permanent sections are sent off to the pathologist rather than the frozen sections integral to conventional Mohs.
Dr. Marmur relies upon slow Mohs, with "bread-loafing" of the central tumor by the pathologist, because the permanent sections better preserve the tumor’s microscopic features. Interpreting atypical melanocytes in frozen sections can be quite a challenge. However, she added, some Mohs surgeons have found that using rapid immunostains also markedly improves the sensitivity and specificity of frozen sections in lentigo maligna surgery.
Slow Mohs takes place over the course of days, she said. "Basically, you do your Wood’s lamp to define the lesion diameter, you measure out your margins, you excise the tumor, pack the area with a bandage, and send the patient home. You rush your pathology, and you don’t do any reconstruction until you get the margins clear."
A pathology report that comes back stating narrow margins are present is "a heart stopper," she added.
"You have the option of observing the area if the margin is clear but the tumor was close to the margin. That’s a good approach for an elderly patient or when the lentigo maligna was in a cosmetically important area."
Lentigo maligna melanoma accounts for 4% of all cases of melanoma. It typically arises on sun-damaged skin in individuals in their 70s or older. Common sites include the malar area, forehead, nose, and temple. The differential diagnosis includes seborrheic keratosis, pigmented actinic keratosis, and pigmented nevus.