A patient undergoes micrographic dermatologic surgery for recurrent basal cell carcinoma. Only one of the four blocks of tissue processed is shown. Deep to the helical cartilage are tumor cells with elongated and hyperchromatic nuclei, visible cytoplasm, and scattered mitotic activity and necrosis surrounding dissecting keloidal collagen.
In order to differentiate from other malignant simulators and inflammation, ber-EP4 immunohistochemistry is performed (shown), along with cytokeratins (including CK20), S-100 and Melan-A. Only ber-EP4 stained the neoplastic cells (shown). What is the appropriate next step?