Intraoperative Indocyanine Green Fluorescence Enables Primary Tumor Localization and Treatment De-Escalation in SCCUP: A Case Report.

Abstract

Unknown primary cancer in the head and neck presents a difficult surgical treatment dilemma. Patients with squamous cell carcinoma of unknown primary (SCCUP) typically present with an enlarging neck mass found on biopsy but with no indication of primary site on diagnostic exams such as flexible laryngoscopy, CT, MRI, and/or PET/CT. Failure to identify primary sites eliminates surgical treatment as an option, pushing patients toward definitive chemoradiation with associated side effects. Indocyanine green (ICG) has been used to identify primary carcinoma in known oropharyngeal squamous cell carcinoma while using transoral robotic surgery (TORS). In this case, we injected ICG intraoperatively in a patient with SCCUP to help with the real-time localization of ICG in the tumor. ICG fluorescence successfully identified a previously undetected primary lesion within the oropharynx during TORS, which enabled precise surgical excision of the tumor. This case demonstrates the potential of ICG-guided TORS to localize primary tumors in SCCUP patients, offering a pathway to surgical treatment and potentially reducing reliance on chemoradiation.