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New Microscopy Aids Treatment in Lentigo Maligna Melanoma

A new type of microscopy can help physicians accurately determine the margins of lentigo maligna melanoma prior to surgery, allowing for improved precision in the removal of the cancer. These results were recently published in the JAMA Dermatology.

Lentigo maligna melanoma (LMM) is a type of melanoma that acts differently than more common types of melanoma. LMM tends to grow large at its site of origin on the skin, without spreading to distant sites in the body. It often occurs in elderly individuals, at sites of direct exposure to the sun, such as the face.

Due to its rarity, standard treatment for LMM remains controversial, but often includes the surgical removal of the site. Because LMM is prone to recurrences, physicians try to remove all the cancer plus small margins of healthy tissue around the entire area of cancer.

Since LMM often occurs on the face and grows large in size, aesthetics remains an important component to care. Therefore, surgeons do not want to remove excessive amounts of skin during the surgery, but enough so that all cancer cells are eliminated.

One difficulty in treating LMM is its lack of color in some areas, so the cancerous spot blends in with the rest of the normal skin. Therefore, examination of the surgically removed specimens under a microscope is the only way in which physicians really know if they have removed all the cancer.

A new type of microscopy, referred to as in vivo reflectance confocal microscopy (RCM), actually allows a physician to assess and determine the precise area of cancer, even under the skin and/or areas that appear healthy, prior to surgery. The physician can then plot the exact areas of removal on a patient’s intact skin.

Researchers from Australia and Ireland recently conducted a clinical trial to further evaluate the effectiveness of RCM for patients with LMM. The trial included 37 patients with lentiga maligna, 5 of whom had LMM.

Physicians first performed standard procedures for determining where to surgically remove the sites of LM or LMM. Then they performed RCM and compared the results. The surgical specimens were then analyzed in the laboratory to determine the accuracy of the results of RCM.

Results from RCM ultimately changed treatment decisions in 73% of patients.
All surgical specimens based on RCM results, except for 2, had no cancer cells in the margins. The 2 that needed wider margins were greater than 6 cm in diameter.
The researchers concluded that for patients with LMM, “In vivo RCM can provide valuable information facilitating optimal patient care management,” as accuracy in placement of surgical margins remains difficult with current standard methods.

Reference: Guitera P, Moloney F, Menzie S, et al. Improving Management and Patient Care in Lentigo Maligna by Mapping With In Vivo Confocal Microscopy. JAMA Dermatology. 1-7. doi:10.1001/jamadermatol.2013.2301. Published online April 3, 2013.