Spindle Cell Papillary Thyroid Carcinoma (SC-PTC): A Rare and Challenging Case in Thyroid Pathology

Spindle cell PTC (SC-PTC) is an exceedingly rare PTC subtype believed to have a favorable prognosis. However, a clear and precise definition of SC-PTC is still lacking. Currently, spindle cells in SC-PTC are regarded as a form of metaplasia, wherein follicular carcinomatous cells transform into mesenchymal-like cells devoid of papillary nuclear features. We report the case of a 45-year-old woman diagnosed with spindle cell PTC. The patient presented cervical swelling that progressed gradually over a span of 2-years without causing compressive symptoms. Clinical examination revealed a multinodular goiter, while neck ultrasonography identified a hypoechogenic nodule measuring 4 cm in length in the right lobe [Tirads 4]. Fine needle aspiration (FNA) of this nodule showed follicular neoplasm or suspicion for follicular neoplasm (FN/SFN) [Category IV]. Subsequently, the patient underwent a total thyroidectomy. Following the histological examination of the specimen complemented by immunohistochemical study, a diagnosis of Spindle cell PTC was made. Therefore, we aim to present this uncommon occurrence, which occasionally manifests in papillary thyroid carcinoma.