SAT-361 - Papillary Thyroid Carcinoma with Extensive Locoregional Invasion and Internal Jugular Vein Tumor Thrombus

Background:
Papillary thyroid carcinoma (PTC) is generally associated with indolent behavior and favorable outcomes. Rarely, PTC may exhibit aggressive features, including extensive extrathyroidal extension and invasion of major cervical vascular structures. Tumor thrombus involving the internal jugular vein is exceptionally uncommon and reflects advanced disease with significant prognostic implications.

Case Presentation:
A 67-year-old woman presented for evaluation of a right-sided cervical mass. She reported no symptoms of thyroid dysfunction or compressive complaints and had no history of neck irradiation or family history of thyroid malignancy. Diagnostic evaluation led to surgical management with right hemithyroidectomy and right neck dissection.
Histopathologic examination demonstrated papillary thyroid carcinoma, predominantly classic subtype, measuring 9.2 cm in greatest dimension. The tumor exhibited extensive extrathyroidal extension with invasion into adjacent skeletal muscle and adipose tissue, as well as direct invasion of the internal jugular vein with associated tumor thrombus formation. The carcinoma focally involved the medial, posterior, and anterior surgical margins. Regional lymph node metastases were identified in 8 of 44 examined lymph nodes. Pathologic staging was pT4b pN1b, consistent with advanced locoregional disease.

Discussion:
Macroscopic vascular invasion and tumor thrombus formation in PTC are rare and signify biologically aggressive disease. Such features are associated with increased risks of locoregional recurrence and disease-specific mortality. Surgical management is complex and necessitates careful preoperative assessment and multidisciplinary coordination. This case underscores that aggressive PTC may occur even in the absence of traditional risk factors and highlights the importance of comprehensive pathologic evaluation for accurate staging and postoperative risk stratification.

Conclusion:
This case represents an uncommon presentation of papillary thyroid carcinoma characterized by extensive locoregional invasion and internal jugular vein tumor thrombus. Recognition of these aggressive features is critical for prognostication, guiding adjuvant therapy, and informing long-term surveillance strategies.

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