Papillary thyroid carcinoma (PTC) is considered as a relatively common type of malignancy showing a wide morphologic spectrum. Different variants of this tumor have been reported. Among PTC variants, PTC with nodular fasciitis-like stroma (PTCFLS) is rare. This variant consists of stromal components rich in spindle cells and accounts for 60-80% of tumors. In addition, there are small foci of epithelial components in PTCFLS though its features are similar to conventional PTC. In this case study, we present a new case with PTCFLS. The case is a 28-year-old female who was referred to the ENT clinic due to a painless mass on the anterior part of her neck. The mass showed a gradual increase in size over the 6 months prior to her referral. Thyroid test results were normal. Ultrasound imaging demonstrated an 84 × 36 mm heterogeneous nodule in the right thyroid lobe without calcifications but increased vascularity. There were also some reactive lymph nodes in both sub-mandibular areas. An ultrasound-guided fine-needle aspiration (FNA) biopsy of the right thyroid lobe nodule revealed a benign thyroid adenomatoid nodule. Following right thyroid lobectomy, final pathologic studies confirmed a diagnosis of PTC with exuberant fibromatosis-like stroma. In the 20-day post-surgery visit, the patient was found asymptomatic. Re-evaluation of the left thyroid lobe and follow-up were recommended. In this study, a diagnosis of a rare variant of PTC, i.e., PTC-FLS, was made through a combination of ultrasonography, fine needle aspiration cytology, and histological examination.
Keywords: Fibromatosis-like stroma; Neck mass; Papillary thyroid carcinoma.