The use of imiquimod to minimize the surgical defect when excising invasive malignant melanoma surrounded by extensive melanoma in situ, lentiginous type.

Malignant melanoma in situ, lentiginous type (LM), is a precursor lesion for malignant melanoma, lentiginous type (LMM). LM is characterized as an irregular, pigmented patch that is most commonly found on chronically sun-exposed skin, including the head and neck. LM is shown to be increasing in incidence and is the most prevalent subtype of in situ melanoma. Although LM constitutes only 4% to 15% of all melanomas, it is the most common type of head and neck melanoma. The progression of LM to its invasive form, LMM, is estimated to occur after 10 to 15 years. During this time, there is a protracted radial growth phase that is unique to LM among the in situ melanomas. Local recurrence of LMM is reported to account for 37% of all locally recurrent melanomas, which is most likely influenced by the clinical and histopathologic challenge of defining tumor margins in the context of chronically sun exposed skin. Although the recommended surgical margin for melanoma in situ is 5 mm, it has been well documented that, for the LM subtype, this is often inadequate and most likely contributes to local recurrence. The formation of LM, as well as its progression to LMM, is thought to involve the decrease in cell-mediated immunity in sun-damaged skin. Although first-line recommended treatment for LM is surgical excision, noninvasive therapies may be considered in certain clinical situations. Imiquimod is a topical immune-modulator acting on Toll-like receptors and has been shown to be a potent enhancer of innate and acquired immune responses. Various small open-label studies have reported treatment of LM with 5% imiquimod cream. The current study reports the use of this topical drug as an adjunct to surgical excision when treating extensive LM with focal invasive malignant melanoma.