Clinicopathologic features of solid variant papillary thyroid cancer

Abstract

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. 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. 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. 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.