Fine needle aspiration biopsy of three cases of squamous cell carcinoma presenting as a thyroid mass: cytological findings and differential diagnosis.

OBJECTIVE

Primary squamous cell carcinomas of the thyroid gland are extremely rare, comprising about 1% of thyroid malignancies. Although squamous cell carcinomas are readily identified as such on aspiration cytology in the majority of cases, the differentiation of primary versus metastatic tumour might not always be easy. Herein, we report three cases of squamous cell carcinomas involving the thyroid gland.

METHODS

Fine needle aspiration cytology (FNAC) was performed in three patients with a thyroid mass using standard guidelines. Smears were stained with Diff-Quik and Papanicolaou stains.

RESULTS

Two patients were male and one was female, aged 59, 45 and 35 years, respectively. In all three patients a thyroid mass was present. FNAC smears in all cases showed cytological features of squamous cell carcinoma including keratinization and necrosis. After clinical and cytological correlation, one case appeared to be primary, one case metastatic, and in the third case no additional clinical information or biopsy follow-up was available for further characterization.

CONCLUSIONS

Because primary squamous cell carcinoma of the thyroid is a rare finding, metastatic squamous cell carcinoma should always be excluded first. Metastatic disease usually presents in the setting of widespread malignancy, therefore a dedicated clinical and radiological investigation is necessary in these cases. In both clinical scenarios the patient's prognosis is poor.