Cervical Paratracheal Bronchogenic Cyst Mimicking Nodal Metastatic Disease in a Colorectal Cancer Patient: Diagnostic Utility of Neck Ultrasound-Guided Fine Needle Aspiration.

Bronchogenic cysts are rare congenital lesions, typically identified in childhood but occasionally found in adults as incidental findings on imaging. In oncology patients, these lesions can present a diagnostic challenge due to their potential to mimic metastatic disease. We report a case of a 78-year-old woman undergoing routine surveillance for Stage II colorectal cancer who was found to have a paratracheal cystic lesion suspicious for malignancy. Ultrasound-guided fine needle aspiration (US-FNA) targeted posterior to the carotid artery and aspirated necrotic material, yielding pathognomonic ciliated epithelium without malignancy. Coupled with absent FDG avidity on PET and negative cultures, cytology confirmed a benign bronchogenic cyst, excluding metastasis and preventing unnecessary treatment. This case underscores that cervical bronchogenic cysts are critical malignancy mimics in oncology patients and demonstrates US-FNA's unique utility in obtaining contamination-free diagnostic samples, overcoming limitations of other approaches, to avert intervention risks during cancer surveillance.