Clinicopathologic features of solid variant papillary thyroid cancer

Abstract

BACKGROUND: Solid variant papillary thyroid cancer (SVPTC) is a rare type of thyroid malignancy whose clinical characteristics remain poorly defined. Therefore, we evaluated the characteristics of 14 patients with SVPTC treated at our institution. METHODS: Of the 6052 patients with papillary thyroid cancer (PTC) evaluated at our institution between January 2008 and December 2011, 14 (0.23%) had SVPTC and were analysed retrospectively. RESULTS: Of the 14 patients with SVPTC, two were men and 12 were women, with a mean age of 48.2 years (range: 33-72 years). The mean follow-up period was 24 months (range: 8-36 months). All patients were assessed preoperatively by ultrasound-guided fine needle aspiration cytology (FNAC), with the diagnosis confirmed by permanent pathology and immunohistochemical staining performed by a specialized endocrine pathologist. Only one patient was diagnosed with SVPTC by preoperative FNAC, whereas 11 (78.6%) were diagnosed with PTC or suspected of having PTC. The mean tumour size was 1.02 ± 0.30 cm, with all tumours less than 2.0 cm in diameter. The infiltrative tumour margins were observed in eight patients (57.1%) and the extrathyroidal invasion in seven (50.0%). The central lymph node metastases were found in five patients (35.7%), and the lateral lymph node metastasis in one (7.1%). No patient experienced tumour recurrence or distant metastasis during follow-up. CONCLUSIONS: Despite the small sample size and the short follow-up period, our results indicate that SVPTC may not be as aggressive a subtype as previously thought.