Lentigo Maligna/Lentigo Maligna Melanoma: Current State of Diagnosis and Treatment

University of Utah, Salt Lake City, Utah, United States
Dermatologic Surgery (Impact Factor: 2.11). 05/2006; 32(4):493-504. DOI: 10.1111/j.1524-4725.2006.32102.x
Source: PubMed


Lentigo maligna (LM) is a subtype of melanoma in situ that typically develops on sun-damaged skin. Presentation may be quite subtle and delayed diagnosis is common. Clinical margins are often ill defined. Histologic evaluation can be difficult due to the widespread atypical melanocytes that are present in the background of long-standing sun damage. Recurrence following standard therapies is common.
To review the clinical features, histopathology, and treatment options for LM. Emphasis is placed on recent advances in the treatment of LM.
Literature review.
The estimated lifetime risk of LM progressing to LM melanoma is 5%. Standard excision of LM with 5 mm margins is insufficient in 50% of cases. The recurrence rate with standard excision ranges from 8 to 20%. Mohs surgery and staged excision may offer better margin control and lower recurrence rates (4-5%). Estimates of recurrence rates following nonsurgical therapies such as cryosurgery, radiotherapy, electrodessication and curettage, laser surgery, and topical medications range from 20 to 100% at 5 years.
Adequate treatment of LM requires a comprehensive knowledge of the diagnostic features, histopathology, and treatment options. Surgical modalities with meticulous evaluation of tissue margins appears to offer the lowest rates of disease recurrence.

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    • "As with SSM, it is only after vertical spread into the dermis that the lesions present a serious threat (Smoller, 2006). Nevertheless, LMM is very different from SSM. Lentigo maligna melanoma is less frequently derived from naevi, has a much later age-of-onset, exhibits characteristic changes in the epidermis (atrophy) and dermis (solar elastosis), and shows a distinct pattern of MC distribution (lentiginous versus pagetoid spread) (reviewed in McKenna et al., 2006). Hence, LMM appears to develop via a unique pathogenic mechanism dominated by chronic sun damage (CSD) over many decades. "
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    • "Furthermore, determination of the peripheral margins of LM clinically and pathologically also represents another challenge . Clinically, LM is often amelanotic peripherally, and can spread far beyond the visible margins (McKenna et al., 2006). Dermoscopy (Schiffner et al., 2000; Robinson, 2004; Stante et al., 2005) and Wood's light examination (Jeneby et al., 2001) have been described as useful techniques to better define the extent of the lesion. "
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    ABSTRACT: Limited studies have reported the in vivo reflectance confocal microscopy (RCM) features of lentigo maligna (LM). A total of 64 RCM features were scored retrospectively and blinded to diagnosis in a consecutive series of RCM sampled, clinically equivocal, macules of the face (n=81 LM, n=203 benign macules (BMs)). In addition to describing RCM diagnostic features for LM (univariate), an algorithm was developed (LM score) to distinguish LM from BM. This comprised two major features each scoring +2 points (nonedged papillae and round large pagetoid cells > 20 microm), and four minor features; three scored +1 point each (three or more atypical cells at the dermoepidermal junction in five 0.5 x 0.5 mm(2) fields, follicular localization of atypical cells, and nucleated cells within the dermal papillae), and one (negative) feature scored -1 point (a broadened honeycomb pattern). A LM score of > or = 2 resulted in a sensitivity of 85% and specificity of 76% for the diagnosis of LM (odds ratio (OR) for LM 18.6; 95% confidence interval: 9.3-37.1). The algorithm was equally effective in the diagnosis of amelanotic lesions and showed good interobserver reproducibility (87%). In a test set of 29 LMs and 44 BMs, the OR for LM was 60.7 (confidence interval: 11.9-309) (93% sensitivity, 82% specificity).
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