Effectiveness of imiquimod limited to dermal melanoma metastases, with simultaneous resistance of subcutaneous metastasis.

Successful management of epithelial skin cancers with imiquimod 5% cream (Aldara), an immunomodulatory agent, led to speculation that it may promote an immune response against melanoma. Studies, mostly case reports, have assessed the value of imiquimod as a topical treatment for dermal melanoma metastases that prove difficult to manage surgically. The precise value of imiquimod, however, in treatment of dermal and subcutaneous metastases remains unclear. A case at our institution elucidates histopathologically that subcutaneous metastases may progress despite excellent treatment of superficial dermis in the same location. In preparation for a clinical trial using imiquimod to treat patients with dermal melanoma metastases, we have treated several patients off protocol. We present a case report in which the observed changes are documented photographically and histologically. The patient experienced dramatic improvement in the locally treated dermis with concurrent regional treatment failure in the subcutaneous space. Our experience supports growing evidence that imiquimod for some provides an effective option for dermal disease. The unique histological documentation we provide regarding the differential effectiveness of imiquimod in treating various tissue components may help guide future investigations regarding optimal clinical application of imiquimod therapy for melanoma metastases.