TLR7 and skin basal cell carcinoma: Imiquimod (IMQ) is a Toll-like receptor 7 (TLR7) agonist used for the in situ treatment of cutaneous squamous cell carcinoma, superficial basal cell carcinoma (BCC), cutaneous malignant melanoma metastases, and precursor lesions of actinic keratosis [18,19].