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A 77-year-old man presents for evaluation of a darkened area on his right cheek that his wife first noted about 1 year ago. She states that the lesion has been slowly enlarging in size and possibly darkening in coloration. The patient is unconcerned and, at first, refused a biopsy. He has no history of skin cancer but received treatment several years ago for solar keratoses on his hands. Physical examination reveals a hyperpigmented macule. Dermoscopic examination reveals asymmetric pigmented follicular openings and greyish globules and dots.
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Lentigo maligna is an in situ subtype of melanoma that arises on skin that has been chronically exposed to sunlight. The condition is more common in males with a peak incidence between the ages of 60 and 80 years.1 The face, scalp, and neck are the most commonly affected sites although location on the extremities and trunk has been reported.2 Over 50% of cases occur on the cheeks.
Lesions first present as macular skin discoloration with hues ranging from light to dark brown. Lesions may also contain shades of pink, red, or white. A dermoscopic examination may reveal asymmetric pigmented follicular openings, light brown pseudo-networks, light rhomboidal structures, and peripheral gray dots and globules.
Histology reveals evidence of solar damage accompanied by increased density of melanocytes at the dermal-epidermal junction with extension along adnexal structures and varying degrees of nuclear atypia. Although slow-growing, lentigo maligna may progress to lentigo malignant melanoma with a lifetime risk ranging from 5% to 50%.3 Factors indicative of transformation include lesion thickening, shades of black and blue, and ulceration.
The standard of care for lentigo maligna is excision with 0.5 cm margins; borders may be indistinct clinically. A staged excision and Mohs micrographic surgery are associated with lower recurrence rates.4,5 Surgery may not be a viable option because of location, age, comorbidities, or patient preference. Alternative treatment modalities, therefore, include radiation therapy and topical imiquimod.6,7 Pretreatment of larger lesions with imiquimod in advance of surgery may enhance aesthetic outcome.8
Lawrence Schiffman, DO, is the founder and director of Miami Skin Dr in Doral, Florida. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
References
1. Oakley A. Lentigo maligna and lentigo maligna melanoma. DermNet. Accessed June 20, 2023. https://dermnetnz.org/topics/lentigo-maligna-and-lentigo-maligna-melanoma
2. Martínez-Leboráns L, Garcías-Ladaria J, Oliver-Martínez V, Alegre de Miquel V. Extrafacial lentigo maligna: a report on 14 cases and a review of the literature. Actas Dermosifiliogr. 2016;107(8):e57-63. doi:10.1016/j.ad.2015.10.018
3. Iznardo H, Garcia-Melendo C, Yélamos O. Lentigo maligna: clinical presentation and appropriate management. Clin Cosmet Investig Dermatol. 2020;13:837-855. doi:10.2147/CCID.S224738
4. Hazan C, Dusza SW, Delgado R, Busam KJ, Halpern AC, Nehal KS. Staged excision for lentigo maligna and lentigo maligna melanoma: a retrospective analysis of 117 cases. J Am Acad Dermatol. 2008;58(1):142-148. doi:10.1016/j.jaad.2007.09.023
5. Sharma AN, Foulad DP, Doan L, Lee PK, Atanaskova Mesinkovska N. Mohs surgery for the treatment of lentigo maligna and lentigo maligna melanoma — a systematic review. J Dermatolog Treat. 2021;32(2):157-163. doi:10.1080/09546634.2019.1690624
6. Hendrickx A, Cozzio A, Plasswilm L, Panje CM. Radiotherapy for lentigo maligna and lentigo maligna melanoma – a systematic review. Radiat Oncol. 2020;15(1):174. doi:10.1186/s13014-020-01615-2
7. Kirtschig G, van Meurs T, van Doorn R. Twelve-week treatment of lentigo maligna with imiquimod results in a high and sustained clearance rate. Acta Derm Venereol. 2015;95(1):83-85. doi:10.2340/00015555-1861
8. Daude M, Dinulescu M, Nguyen JM, et al. Efficacy of imiquimod in the management of lentigo maligna. J Eur Acad Dermatol Venereol. 2023 Apr 27. doi:10.1111/jdv.19141
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