Squamous Cell Carcinoma (SCC) of the Oral Cavity

The purpose of this study is to get images (pictures) of oral lesions, which occur inside the mouth, before the patient's surgery using a special camera. These pictures will be used in our research to evaluate a new technology that uses a laser and takes pictures of the microscopic structure of tissue. The technology is called "reflectance confocal microscopy." We would like to compare what the camera sees to biopsies (pathology) of the same area. We will evaluate the pictures obtained from the patient to determine whether this technology may be useful in the future. We hope this technology can be used as a tool for early diagnosis of oral cancers and for guiding surgery.

The goal of this Phase 1 clinical trial is to evaluate the safety and feasibility of nivolumab-IRDye800CW (nivo800) as a molecular imaging agent in adults with biopsy-confirmed or presumed head and neck squamous cell carcinoma (HNSCC) who are scheduled to undergo standard-of-care surgical resection. The main questions it aims to answer are: * Is nivolumab-IRDye800CW (nivo800) safe when administered before surgery, as measured by the occurrence of clinically significant Grade ≥2 adverse events that are possibly, probably, or definitely related to the study drug? * What is the extent of pathological response at each dose level, including residual viable tumor, fibrosis, necrosis, and tumor-infiltrating lymphocyte characteristics? Participants will: * Receive two intravenous infusions during the preoperative period, approximately 2-3 weeks before surgery and again 1-2 days before surgery. * Undergo standard-of-care surgical resection with collection of tumor and lymph node specimens for pathological and imaging studies.