7825 Papillary Thyroid Cancer with Left Neck Level IV Nodal Metastasis & Left Paratracheal Metastasis

Abstract Disclosure: M.J. Barroso: None. I. Noemi: None. M.A. Martínez: None. S. Pino: None. C. Cue: None. S. Espinosa: None. S. Barroso: None. Incidental Papillary Thyroid Cancer with Left Neck Level IV Nodal Metastasis & Subsequent Left Mediastinal Paratracheal Metastasis Papillary thyroid cancer (PTC) is a well-differentiated epithelial derived primary thyroid neoplasia. Being the most common primary thyroid malignancy it comprises about 80% of thyroid cancer cases. It often invades nearby structures, with 10-20% of patients showing metastasis, typically to local lymph nodes, at diagnosis, and tends not to affect the overall prognosis of the disease. We present the case of a 22 year old female patient with no relevant family or medical history. As a medical student she underwent a random neck ultrasound during a clinical rotation, with the incidental finding of a left thyroid nodule with features of malignancy. The nodule was characterized by having irregular borders, microcalcifications and both solid and cystic components. Laboratory findings included elevated thyroglobulin of 445.1 ng/mL (reference range 2.8 - 40.9) with TSH, and T3 and T4 within normal limits. A follow up ultrasound revealed findings compatible with left level IV lymph node metastasis. A subsequent fine needle aspiration biopsy was performed, confirming the diagnosis of papillary thyroid carcinoma with left neck level IV lymph node metastasis. The patient underwent a total thyroidectomy with lymph node resection. Postoperatively, the patient experienced the complication of laryngeal nerve palsy resolving spontaneously two months later with no need of additional intervention. The patient received adjuvant radioactive iodine therapy. However, the patient experienced symptoms compatible with hypothyroidism despite being on thyroid hormone replacement therapy. Postoperative follow up laboratory test revealed persistent thyroglobulin elevation, suggestive of cancer recurrence. A chest contrast CT and PET scan revealed a 2.15 cm mediastinal mass, suggesting left paratracheal lymphadenopathy with evidence of papillary cancer recurrence. The patient subsequently underwent a left robotic resection of paratracheal mediastinal mass, with a pathology report of the specimen confirming metastatic papillary thyroid carcinoma present in one lymph node with extranodal extension. The patient denied additional therapy with external beam radiation and has since been monitored rigorously, on thyroid replacement therapy prioritizing TSH suppression to minimize the risk of further recurrence.The presence of mediastinal paratracheal nodal metastasis, a rare site of invasion present in about 3% of patients with PTC raises the question of the indications for extended lymph node resection, the benefit of additional radiation therapy, and increased rigor regarding postoperative thyroid replacement therapy dosage, TSH and thyroglobulin levels as an alternative to radiation in order to promptly detect and avoid recurrence in high-risk patients. Presentation: 6/1/2024