The purpose of this study is to evaluate a new instrument that shines light and takes digital pictures of skin. The goal is to develop a technique that may enable fast and accurate assessment of surgical margins in the excision of basal cell carcinoma (BCC) or squamous cell carcinoma (SCC). The investigators will evaluate the pictures obtained by the confocal microscope to determine whether this technique may be useful in the future for helping Mohs surgeons remove cancers. In the future, patients may benefit with shorter surgery and improved care.

Inclusion Criteria:

• Patients undergoing Mohs surgery for basal cell carcinoma (BCC )or squamous cell carcinoma (SCC). .
• Ability to sign informed consent.
• Age ≥ 18 years.

Exclusion Criteria:

• Mohs surgery located on a site that may not be convenient to confocal imaging.
• Inability to give informed consent.
• Inability to tolerate imaging procedure (i.e., remain relatively still for multiple short durations of 3-4 minutes) over a total time of 20 minutes.

Patients in Dermatology clinics at MSKCC