Analysis of primary and secondary squamous cell carcinoma of the thyroid gland: a cross-sectional study

Background: Squamous cell carcinoma of the thyroid (SCCT) is a kind of rare malignant disease. This study aimed to analyse the clinical characteristics of patients with primary SCCT (PSCCT) and secondary SCCT (SSCCT). Methods: The medical records of seventeen patients with PSCCT and six patients with SSCCT were reviewed. Clinical symptoms, ultrasound, and pathological characteristics were compared between the two groups. Results: The mean age of diagnosis was approximately 56 years old in each group. The most common chief complaint of the patients was neck mass in both groups. The percentage of patients with cough (P=0.008) or weight loss (P=0.021) was higher in the SSCCT group than the PSCCT group. The mean size of the tumor in the PSCCT group was larger than that in the SSCCT group (3.382 +/- 2.011 vs. 1.950 +/- 0.794 cm, P=0.024). Papillary thyroid carcinoma ( PTC) could be combined with or recur as PSCCT. Kaplan-Meier analysis indicated that the mean survival times after diagnosis were 17.053 months in the PSCCT patients and 13.500 months in the SSCCT patients. Multivariate survival analysis using a Cox regression model demonstrated that predictors of overall survival (OS) in PSCCT patients included age (P=0.020), enlarged cervical lymph node (P=0.017), radical operation (P=4.82x10(-3)), and PTC (P=0.03). Conclusions: SCCT is aggressive, with neck mass being the most common chief complaint. There were several different characteristics between PSCCT and SSCCT. PTC could be combined with or recur as PSCCT. Age, enlarged cervical lymph node, radical operation, and PTC were the predictors of OS in PSCCT patients.