In this report, we describe a case of ectopic cervical thymoma (medullary or type A thymoma, according to the WHO classification) located in the anterior cervical region (thyroid topography) that was submitted to ultrasound-guided fine-needle aspiration biopsy. The cytologic smears were moderately cellular to very cellular and were composed of numerous spindle-shaped cells placed predominantly in tissue fragments, with no specific arrangement. Isolated spindle-shaped cells were also present in a hemorrhagic background. The nuclei were elongated with finely granular chromatin and inconspicuous nucleoli. Mitosis, nuclear atypia, and necrosis were not detected. There was a scarce lymphoid population of small lymphocytes. The cytologic aspects, the correlation with histologic findings, and the differential cytologic diagnosis are reviewed.