Lentigo Maligna

Background

• Lentigo maligna is a type of melanoma in situ that typically appears on chronically sun-exposed skin, usually on the face or neck. Lentigo maligna can progress to invasive lentigo maligna melanoma.
• Lentigo maligna most commonly affects patients > 60 years old, and its incidence has been increasing over the past decade.
• Treatment of lentigo maligna generally has a high cure rate, but patients may still be at increased risk of developing a second primary cutaneous melanoma.

Evaluation

• Suspect lentigo maligna in older adult patients with pigmented macule or patch on the face, head, neck, arms, or other sun-exposed areas.
• Lesions are typically tan-brown with asymmetric, irregular borders, and range in size from a few millimeters to a few centimeters depending on the age of the lesion. Amelanotic lesions occur, but are rare.
• Consider Wood lamp or dermoscopy for a more detailed exam of suspicious lesions, and obtain a biopsy to confirm the diagnosis.
• Excisional biopsy is preferred for histologic diagnosis, but often is not possible due to the size and/or location of the lesion, so smaller "scouting" biopsies including shave or punch biopsy may be used.

Management

• Consider surgical excision as the preferred treatment for lentigo maligna (Weak recommendation).
• Consider surgical techniques that allow for an extensive histologic examination of margins, such as Mohs micrographic surgery or staged excision techniques with en-face sections or thin step sectioning, for the excision of lentigo maligna (Weak recommendation).
• For wide excision of melanoma in situ, consider surgical margins of 0.5-1.0 cm to clear a possible subclinical extension beyond visible margins (Weak recommendation).
• Consider larger surgical margins for larger lesions, particularly those on the head and neck, to ensure the clearance of subclinical extension.
• Evaluation of tumor debulking is necessary to assess for subclinical invasion or high risk for recurrence.
• Consider nonsurgical management, such as imiquimod 5% topically or radiation therapy for patients with either contraindications for surgery or positive margins after a surgical excision (Weak recommendation).