Topical Imiquimod for Lentigo Maligna in a Nonagenarian

Lentigo maligna (LM) represents melanoma in situ and predominantly affects elderly individuals, typically arising on chronically sun-exposed skin of the head and neck. Although LM is characterized by slow horizontal growth and generally favourable prognosis, progression to invasive lentigo maligna melanoma may occur, making timely and effective treatment essential. Surgical excision remains the standard of care; however, advanced age, comorbidities, lesion size, and cosmetic or functional considerations may limit surgical feasibility.

We report the case of a 93-year-old woman with no prior history of skin cancer who presented with a gradually enlarging pigmented lesion on the forehead. Clinical examination revealed an irregularly pigmented macule measuring 25 × 27 mm. Multiple mapping biopsies confirmed melanoma in situ of the lentigo maligna type, with adnexal extension and no evidence of dermal invasion. Given the patient's advanced age and lesion location, a non-surgical approach was selected. Topical imiquimod 5% cream was applied five times per week for 12 weeks to the visible lesion and to a 20 mm margin around it. The patient was monitored closely throughout the treatment. Local inflammatory reactions were mild to moderate, consisting mainly of erythema, crusting, and superficial erosion, without systemic adverse effects. At treatment completion, marked clinical improvement with near-complete resolution of pigmentation was observed. Follow-up dermoscopic evaluation demonstrated only minimal residual granular pigmentation. Post-treatment mapping biopsies confirmed complete histological clearance of atypical melanocytic cells.

This case illustrates that topical imiquimod may serve as a safe and effective alternative to surgery in carefully selected elderly patients with lentigo maligna. Close clinical follow-up and histological confirmation of clearance are essential to ensure treatment success and durable outcomes.