What is the treatment for a suspected lentigo maligna melanoma?

Treatment of Lentigo Maligna Melanoma

The standard treatment for suspected lentigo maligna melanoma is complete surgical excision with appropriate margins based on the depth of the lesion. 1

Diagnosis and Initial Assessment

• Any patient with a suspicious pigmented lesion should be referred urgently to a dermatologist or surgeon with expertise in pigmented lesions 1
• Specialists should ensure patients with suspicious lesions are seen within 2 weeks of referral 1
• A full skin examination should be performed, documenting the site and size of the pigmented lesion 1
• Clinical photographs may be helpful for documentation 1
• Examination should include checking for lymphadenopathy and hepatomegaly 1

Biopsy Approach

• For suspected melanoma, an excisional biopsy should be performed as a full-thickness skin biopsy that includes the entire lesion with a 2-5 mm clinical margin and a cuff of subdermal fat 1
• Shave and punch biopsies are not recommended as they make pathological staging impossible 1
• Incisional biopsy is occasionally acceptable for facial lentigo maligna to establish diagnosis, but should only be performed by specialists within the skin cancer multidisciplinary team 1

Treatment of Lentigo Maligna (Melanoma in situ)

• The standard treatment for lentigo maligna is surgical excision with a margin of 0.5 cm 1
• Complete excision with clear histological margins is the goal as lentigo maligna has no potential for metastatic spread 1
• For elderly patients or when complete excision is impossible or contraindicated, alternative options include:
  • Radiotherapy 1
  • CO2 laser 1
  • Cryotherapy 1
• The reason for choosing non-surgical treatment should be clearly documented 1

Treatment of Invasive Lentigo Maligna Melanoma

Surgical margins depend on the Breslow thickness:

• For melanomas <1 mm in depth: 1 cm margin is safe and appropriate 1
• For melanomas 1-2 mm in depth: minimum 1 cm margin, with 2 cm preferred where functionally and cosmetically sensible 1
• For melanomas 2-4 mm in depth: 2 cm margins are recommended 1

Special Considerations for Facial Lesions

• Lentigo maligna on the face has a higher risk of recurrence compared to other in situ melanomas, often due to a "field effect" where atypical melanocytes extend laterally but are not clinically detectable 1
• Mohs micrographic surgery may be considered for facial lesions as it has the lowest recurrence rate at 4-5% 2
• Conventional surgery, cryotherapy, and radiotherapy yield recurrence rates of approximately 7-10% 2

Follow-up Recommendations

• After complete excision with adequate margins, the risk of local recurrence for melanoma in situ is negligible 1
• Patients should be followed annually throughout life to detect potential second melanomas 1
• Self-surveillance should be encouraged with appropriate patient education 1

Common Pitfalls to Avoid

• Partial removal of melanocytic lesions can result in pseudomelanoma, causing needless anxiety and diagnostic confusion 1
• Prophylactic excision of pigmented lesions without suspicious features is not recommended 1
• Incisional biopsies should not be performed in primary care settings 1
• Underestimating the extent of lentigo maligna, particularly on the face, can lead to incomplete excision and recurrence 1, 2