Diagnosis and treatment of solitary fibrous tumors of the thyroid gland: the importance of an appropriate diagnostic approach.

Solitary fibrous tumor (SFT) is a type of fibroblastic neoplasm with characteristic histological features, typically showing cytoplasmic expression of CD34 and nuclear expression of STAT6, associated with NAB2-STAT6 gene fusion. Thyroid localization is exceptionally rare, with only 51 cases reported worldwide to date. Its behavior in the thyroid is generally benign, although it may exhibit rapid growth, and its treatment is primarily surgical. The NAB2-STAT6 gene fusion, detected by immunohistochemistry, is pathognomonic for SFT. As exemplified in the present case, core needle biopsy (CNB) is more likely to provide sufficient material for microscopic, immunohistochemical, and other diagnostic techniques.