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One of the hallmarks of the natural world is variation. For instance, the spectrum of visible light is infinitely varied, and though the difference between the blinding sunlight of midday and the impenetrable blackness of an underground cave is stark, between these extremes lie gradations that the eye cannot always distinguish. Similarly, a key issue faced when assessing the margins of lentigo maligna (LM) is to determine whether melanocytes represent the periphery of melanoma or background melanocytes on sun-damaged skin.
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Despite strong resistance in some surgical circles, the use of margin control surgery (MCS) for treating melanoma is increasing. A range of methods has been described in the literature and this has muddied the waters somewhat, which may explain some of this resistance.
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Though MCS has been used for thick invasive melanoma, the NCCN and various working groups continue to recommend a traditional wide local excision (WLE) in accordance with the established margin guidelines rather than MCS for these invasive cases. Until further studies are published, it seems prudent to generally abide by these guidelines in which the size of the excision margin is determined by the thickness of the invasive melanoma.
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MCS for melanoma in situ (MIS) has gained popularity and wider acceptance in the community. Almost all the literature refers to the treatment of head and neck MIS of the LM type, but MCS has also been used quite widely for other forms of MIS (particularly for cases where excision is difficult in accordance with the recommended margin size). MCS for minimally invasive melanoma on anatomically constrained sites (e.g., the face, nose, acral sites) is currently included in the NCCN. The use of MCS in this context is recommended to include a comprehensive histologic assessment, which is usually a final paraffin margin assessment with dermatopathology review.1,2
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LM is a form of MIS which commonly occurs on sun-exposed skin of the head and neck in the elderly. It represents the precursor lesion of invasive lentigo maligna melanoma (LMM). Like all forms of melanoma, the rate of progressing from in situ disease (LM) to invasive disease (LMM) is unknown. Given that some cases of LM may persist without invasion for a very long time, historically it was not considered a form of MIS. More recent acceptance that LM will evolve into invasive LMM if the patient lives long enough has changed this sentiment, and characterization of LM as a form of MIS has become almost universally accepted. Destructive and chemical therapies may be useful in selected patients and lesions, but surgical excision with meticulous histologic examination of the margins produces the highest cure rate.
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The currently recommended surgical margins for MIS generally range from 0.5 to 1 cm. Unfortunately, these margin recommendations are often not sufficient for LM on the head and neck. With the goal of achieving negative ...