7357 Microscopic Papillary Thyroid Cancer Presenting with Cranial Nerve Palsies due to Metastatic Cervical Lymphadenopathy: A Case Report
Authors: Mukhtar Noha N , Zuo Connie , Haugen Bryan R 
Published: October 2024

Disclosure: N.N. Mukhtar: None. C. Zuo: None. B.R. Haugen: None.

Introduction: Tumors metastasizing to head and neck are considered a rare cause of cranial nerve palsy (CNP). In this report, we describe an unusual presentation of metastatic microscopic follicular variant papillary thyroid cancer (FVPTC) presenting with CNP. Case Summary: A 68-year-old previously healthy female presented to her primary care physician with a 6-week history of difficulty speaking and chewing food. She did not notice any dysphagia, change in voice or shortness of breath. Cranial nerve examination was evident for palatal asymmetry, left-sided uvular and right-sided tongue deviations suggesting right glossopharyngeal and hypoglossal nerve palsies. Neck examination revealed a normal thyroid gland without palpable nodules however, the patient had multiple enlarged painless right cervical lymph nodes (CLN). MRI of the brain was normal. CT of the neck and chest showed enlarged, calcified right level II and III CLN (largest 4x3.5 cm) compressing the right internal jugular vein. In addition, bilateral pulmonary nodules (largest 1.7x1.5 cm) suspicious for metastasis were seen. CT-guided biopsy of left upper lobe lung nodule was consistent with metastatic thyroid cancer (positive PAX-8 and TTF-1 immunostaining). Neck ultrasound did not show any thyroid nodules, but did confirm 4 enlarged right CLN (largest 2.9 cm). The patient was referred to our multidisciplinary clinic for further evaluation. Based on the duration of her symptoms (6 weeks), her CNP was most-likely irreversible and agreement to proceed with total thyroidectomy, central and right lateral neck dissection aiming for complete resection in preparation for future treatment with radioactive iodine. Preoperative thyroglobulin level was 30.7 ng/ml (1.6-50), thyroglobulin antibody 24 U/mL (&lt;40) and TSH 0.6 mIU/L (0.4-4.6). Intra-operatively; the patient had extensive, bulky lymphadenopathy extending to surrounding neck muscles and completely encasing right jugular vein. Histopathological examination of the resected tissue showed a unifocal right thyroid lobe microscopic (6x4x3 mm) infiltrative follicular variant papillary thyroid cancer (FVPTC). No extrathyroidal extension, necrosis, angioinvasion or lymphatic invasion were identified. Mitotic index was 3/ 2mm2. 13 out of 36 lymph nodes were positive for metastatic thyroid cancer (3/3 level II, 2/17 level III, 8/16 level IV), largest was 4.6 cm with extra-nodal extension. The patient was discharged on suppressive dose levothyroxine. Molecular studies: Next generation sequencing of the lung biopsy was negative for BRAFV[6]00E mutation and further molecular analyses are ongoing. Conclusion: This case describes two unique presentations of thyroid cancer; a microscopic FVPTC associated with large lateral cervical lymph node metastasis and, CNP as the initial presentation of thyroid cancer which to our knowledge, has not been reported previously.

Presentation: 6/2/2024