This study is designed as a randomized, prospective study to test the efficacy of imiquimod plus tazarotene in the treatment of LM. Eligible and consented patients will be randomized to one of two treatment groups: 1) topical imiquimod group, or 2) topical imiquimod combined with topical tazarotene group. All patients will undergo a staged surgical excision with rush permanent sections to confirm negative histologic margins. This will be followed by a surgical repair of the defect and long-term follow-up of five years to rule out recurrences. Both groups will have a polygonal excision using 2mm margins per stage.

Objectives

The objectives of the study are:

1. reduce the surgical morbidity of staged excisions which often require multiple stages of surgery in order to verify negative histologic margins
2. investigate the addition of a topical retinoid, to our standard-of-care (topical imiquimod and staged-excision) and evaluate if there is improvement in efficacy
3. to see if treatment of surrounding normal appearing skin with this combination of topical agents reduces recurrence rates compared to staged-excision. Our hypothesis is that the combination of topical agents will better treat the subclinical melanocytic atypia which can give rise to recurrences.

Primary endpoint:

The primary goal is a comparison of the number of stages required for negative histologic margins in the imiquimod plus tazarotene group compared to the imiquimod group. Tumors requiring 5 or more stages in will be combined into one category for data analysis. The Wilcoxon-Mann-Whitney test will be used for statistical comparison.

Secondary endpoints:

1. Comparison of the surgical defect size (mm2) between the study groups. The difference in area between the entire surgical defect and the original tumor (as recorded on transparent plastic) will be calculated for each patient and used as an endpoint.
2. Comparison of skin inflammation between the study groups. Skin inflammation will be recorded as an ordered categorical variable with four categories (0-3) as described in Section 5.
3. The type of surgical repair required (i.e. primary repair, skin flap, skin graft).
4. Immunostaining to evaluate inflammatory infiltrate. Immunostaining will be analyzed as an ordered categorical variable.
5. Recurrence of the tumor at 3 months, 6 months, 12 months, and yearly for the next four years.
6. The proportion of patients with skin ulceration.
7. The relationship between ulceration, skin inflammation and clearance of LM.

Study Procedures A total of eighty patients, over a twelve-month period, will be recruited from one center for this open label study. Forty patients will be randomly assigned to one of two treatment groups as mentioned in the Study Design section. The study will consist of 4 phases: (1) Enrollment and screening period to evaluate skin cancer, measure and trace its perimeter; (2) 12 week treatment with topical application of study drug(s); (3) Surgical excision of treatment site to ensure eradication of the tumor; (4) Follow-up period to rule out recurrences.

All patients must have a biopsy-proven diagnosis of lentigo maligna confirmed by at least two dermatopathologists from the Department of Dermatology at the University of Utah School of Medicine. At the initial examination the clinical borders of the lesion will be defined using a Wood's lamp (360nm) and the perimeter will be outlined with a gentian violet marker and photographed for the medical record. (Wood's lamp examination helps to identify pigmentary alterations of the skin when are sometimes difficult to appreciate under normal lighting conditions.) At the time of enrollment, to rule out an invasive melanoma, all potential study participants will undergo a shave biopsy of their lesion using local anesthesia. Enrollment will not occur until the biopsy has been examined and confirmed to be a lentigo maligna (melanoma in-situ). If an invasive melanoma is found, the patient will be excluded from the study and additional evaluation/therapies implemented. If the patient is enrolled in the study, a piece of their biopsy specimen will be used to perform immunohistochemistry to evaluate the inflammatory infiltrate. A similar series of histochemical staining will be performed at the conclusion of the study using a piece of the excised skin.

Topical imiquimod group:

Patients randomized to this group will have the perimeter of the LM site, as defined by a Wood's lamp examination, drawn on the skin with a gentian violet pen and photographed with a Polaroid camera . One photograph will go to the medical record and the second given to the patient to help identify the proposed treatment area. The gentian violet perimeter will then be copied on transparent plastic to facilitate tumor localization since the tumor is predicted to disappear clinically during treatment. The patients will then treat the LM site two centimeters beyond the perimeter margin with topical imiquimod 5% cream Monday thru Friday of each week for a total of twelve weeks. After three months of topical treatment, a one-month wash out period will be observed to allow for resolution of inflammation that can obscure the pathologist's ability to evaluate the excised tumor/treatment site. A staged excision will then be performed with two millimeter margins around the original tumor perimeter as previously recorded on transparent plastic which will be placed on the patient's skin to outline the perimeter accurately. Once negative margins are confirmed histologically, post-operative defect size will be measured in mm2 and then a plastic surgical repair will be performed to optimize cosmesis.

Topical imiquimod and topical tazarotene 0.1% cream group:

Patients randomized to this group will undergo an identical treatment protocol as the topical imiquimod group with the addition of topical tazarotene 0.1% cream on Saturday and Sunday of each week.

Inclusion Criteria:

• The study population will consist of eighty subjects who are 18 years or older and have a biopsy-proven lentigo maligna.
• The subjects must have a LM that is in a location amenable to treatment with imiquimod, express a willingness and ability to comply with study requirements, and tolerate an outpatient surgical procedure.
• All participants will sign consent documents prior to enrollment.
• The typical age of patient that develops a LM is beyond the child-bearing range.

Exclusion Criteria:

• In the event that a patient with a LM is pregnant, they will be excluded from the study.
• inability to tolerate the surgical procedure
• invasive melanoma
• previous surgery on the site of interest

5 years