TTF1 and Merkel cell skin cancer: A Caucasian woman in her 90s with a past medical history notable for several non-melanoma skin cancers previously treated with Mohs micrographic surgery, WLE, and intralesional 5-fluorouracil injections presented to the dermatology clinic with a concerning lesion on the dorsum of right foot, which was found to be a primary MCC on shave biopsy (positive IHC for CK20 and negative for TTF-1).