Lentigo maligna (LM) is an in situ melanoma that occurs on the face and other sun-exposed areas. It may histologically extend beyond the clinical borders of the lesion; therefore, obtaining clear surgical margins is difficult.
A 55-year-old woman presented with an irregular, brown-to-tan, poorly differentiated, 2.3 × 1.9-cm patch on her right cheek that was accentuated by Wood lamp examination. The hyperpigmented area had been treated 2 years earlier with carbon dioxide laser ablation without biopsy confirmation, but the lesion had recurred and appeared to be darker and larger. A biopsy specimen showed LM (Figure 1). After a thorough discussion of treatment options, including surgical excision, cryotherapy, and radiation therapy, the patient opted for a nonsurgical approach. The discussion to use 5% imiquimod cream, off-label, included a detailed explanation of the risks, potential failure, and departure from the current standard of care. After the patient applied 5% imiquimod cream once or twice a day for 3 months, multiple punch biopsy specimens obtained from the tumor site showed no residual LM (Figure 2). Clinical examination and Wood lamp examination of the area also showed fading of pigmentation and no extension of the lesion.
Chapman MS, Spencer SK, Brennick JB. Histologic Resolution of Melanoma In Situ (Lentigo Maligna) With 5% Imiquimod Cream. Arch Dermatol. 2003;139(7):943-944. doi:10.1001/archderm.139.7.943