The patient was submitted to US-guided FNA:
MICROSCOPIC DESCRIPTION: The smears contain dispersed atypical cells with round to oval, eccentric nuclei with stippled chromatin and a small amount of delicate cytoplasm. Occasional cells have intracytoplasmic granules and intranuclear pseudoinclusions. There are also scattered large cells with hyperchromatic, pleomorphic nuclei. Dense proteinaceous material is seen in the background. The atypical cells are Calcitonin, Chromogranin and Synaptophysin positive. CD56 is equivocal.
The smears contain a mixed population of lymphoid cells, dendritic reticulum cells and tingible body macrophages. The lymphoid cells show no nuclear atypia. No malignant cells are identified.