Challenging management: Lentigo Maligna
Ana-Maria Forsea MD, PhD
Dermatology Department, Elias University Hospital, Carol Davila University of Medicine and Pharmacy Bucharest
A 69 years old woman presented with a large heterogeneously pigmented macule on left cheek, evolving slowly over several years (Figure 1a). Dermoscopy showed polymorphous features, with irregular pseudo-network, asymmetric pigmented follicle openings, dark gray homogenous areas, slate gray dots and globules, gray rhomboidal structures and circles (Figure 1b).
Under the suspicion of Lentigo maligna melanoma, the patient was referred to plastic surgery and underwent wide excision of the lesion. Histopathology report confirmed lentigo maligna, without invasion. Post-operatory follow-up at 4 months showed good clinical results (Figure 2).
At one year post-operatory follow-up, the lesion showed recurrence clinically (Figure 3a) and dermoscopically (Figure 3b).
A conservative approach was attempted, with topical Imiquimod 5% cream, 5 days/week. The treatment was repeatedly interrupted due to irritation and stopped after 3 months, without significant benefit (Figure 4a,b).
Wide re-exicision was decided, as Mohs surgery was not available. The evolution was favorable at 6 months after re-excision (Figure 5), without recurrence at 1 year and 3 years follow-up.
Lentigo maligna is a slowly progressive form of in situ melanoma, occurring on the face and chronically sun-exposed areas in elderly. It must be distinguished from pigmented lesions of the face such as seborrheic keratoses, lentigo solaris or pigmented actinic keratoses, as well as from invasive melanoma. It is difficult to delineate clinically and histopathologically from the surrounding sun-damaged skin. Dermoscopy and, recently, confocal laser microscopy are useful for the non-invasive diagnosis. Multiple biopsies may be necessary for the diagnosis and exclusion of invasion.
Management is challenging due to poorly defined margins, high recurrence rate, large size, cosmetically sensitive location, age-related comorbidities, difficult non-invasive follow-up, scarce evidence for optimal treatment. Complete surgical removal is the golden standard treatment, but often not possible. Reported recurrence rate is 8-20% for wide excision, 0-33% for Mohs micrographic surgery and 0-7% for staged excision. Conservative therapies include radiotherapy (11.5% mean recurrence rate) and topical imiquimod (25% mean recurence rate).
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