SAT536 A Case of Papillary Thyroid Cancer in Multiple Cervical Lymph Nodes, But Not Found in Thyroid Tissue on Pathology

Disclosure: M.A. Green: None. G.Y. Kim: None. Introduction:As technology advances, imaging becomes increasingly frequent and within the thyroid gland nodules can often be detected. After detection comes evaluation and lymph nodes within the neck are an integral part of this step. For that reason, fine needle aspiration (FNA) of cervical lymph nodes is known to lend a hand toward diagnosis. Here we present a patient who was diagnosed with Papillary Thyroid Cancer (PTC) from FNA pathology of a lymph node, but PTC was not noted within pathology of the thyroid tissue after total thyroidectomy. Case Presentation: This patient is a 34 year-old female with a history of ovarian cancer who presented to the clinic for a thyroid nodule and Hashimoto’s disease. A bed side ultrasound noted a right upper pole 1.6 x 0.6 x 0.6 cm thyroid nodule and a solid 1.8 x 1.5 x 0.8 cm nodule superior to the isthmus likely representing a delphian lymph node. As well, significant cervical lymphadenopathy was seen. A biopsy of the right upper pole nodule was nondiagnostic on FNA, but the delphian lymph node superior to the isthmus was positive for PTC. The patient then underwent total thyroidectomy and right and central neck lymph node dissections. Interestingly, PTC was noted in 3 of 27 lymph nodes in the central compartment, 5 of 18 lymph nodes excised with the thyroid tissue with extranodal extension, and 5 of 24 lymph nodes in the right neck compartment, but not noted in the thyroid tissue itself. The largest metastatic dimension of PTC within the cervical lymph nodes was noted to be 3 cm. The pathology noted a 1.0 cm tumor in the right lobe “approaching skeletal muscle” and psammoma bodies within the left lobe. After the patient’s surgery her stimulated thyroglobulin reported as 0.21 NG/mL and thyroglobulin antibody 2 IU/mL. She was then able to receive 30 mCi of I 131 sodium iodide. TSH maintained at goal on levothyroxine 200 mcg daily. Discussion: Diagnosis of PTC within multiple cervical lymph nodes, but not noted on thyroid pathology is very uncommon. It is highly unlikely in our patient that a cancer within the thyroid does not exist and there are theories to postulate this unique finding. These include missed pathology on the dissection, tumor regression prior to removal, or possibly ectopic tissue as the source of PTC. Although in our patient, given the significant amount of positive cervical lymph nodes, it is hard to believe that ectopic tissue away from the neck was the source or that tumor regression occurred. The pathological findings of psammoma bodies suggest the presence of PTC that spread to the lymphatic system. As well, the nature of thyroid removal leads to some destruction of tissue prior to evaluation. This case highlights the importance of thorough lymph node evaluation as a complete part of preoperative PTC assessment. Presentation Date: Saturday, June 17, 2023