Fine-needle aspiration cytology of an intrathyroidal nodule diagnosed as squamous cell carcinoma: A case report

BACKGROUND Both squamous cell carcinoma(SCC) and papillary thyroid carcinoma(PTC) are common malignant tumors in the neck. However, seldom has SCC of the thyroid been diagnosed. Further, cytological features of SCC and PTC have rarely been reported. The significance of fine-needle aspiration cytology(FNAC) in the diagnosis of neck masses has been established. Herein, we present an exceedingly rare case of an intrathyroidal SCC diagnosed using FNAC, along with its cytological features.CASE SUMMARY A 66-year-old man presented with a left-sided neck mass. Ultrasound examination showed an ill-defined nodule. The appearance was hypoechoic with a few hyperechoic spots. FNAC of the left thyroid nodule was performed. A cellular smear was obtained, and it showed a large number of neoplastic cells with rich cytoplasm and poor cell adhesion. Tumor cell nuclei showed coarse nuclear chromatin and a few enlarged prominent nucleoli. An increased nuclear/cytoplasm ratio was observed. Thus, malignancy was diagnosed without a confirmed tumor type. Percutaneous tumor biopsy was performed to make a definite diagnosis. The tumor cells showed typical squamous cell characteristics.CONCLUSION Head and neck SCC and PTC have different cytologies. Measures are needed to ensure accurate diagnosis using FNAC.