Occult papillary thyroid carcinoma presenting as incidental cervical lymph node metastasis

case report

Abstract

Introduction: Papillary thyroid microcarcinoma rarely presents as occult cervical metastasis in the absence of clinical evidence of thyroid cancer, which makes diagnosis difficult and delays treatment. Objective: To report a case of occult cervical lymph node metastasis from papillary thyroid microcarcinoma. Case report: A 52-year-old female physician with a history of Hashimoto’s thyroiditis and hypothyroidism, on levothyroxine therapy, presented without evidence of primary thyroid cancer on ultrasound examination (US). During magnetic resonance imaging performed for investigation of cervical disc herniation, an infraclavicular metastatic cervical lymph node was identified. The patient underwent lymph node biopsy; frozen section and initial immunohistochemical analysis suggested metastatic adenocarcinoma primarily originating from the female genital tract or lung. Further investigation included gynecological evaluation, which was unremarkable, and thyroid ultrasound showing decreased echogenicity and a 0.9 × 0.6 cm calcification. A review of the immunohistochemical analysis revealed papillary thyroid microcarcinoma. The patient underwent total thyroidectomy, cervical neck dissection, TSH suppression, and radioactive iodine therapy. After nine years of follow-up, she remains free of metastatic disease. Conclusion: The authors highlight the incidental diagnosis of occult lymph node metastasis from papillary thyroid carcinoma, supporting the hypothesis that this tumor type should not be considered low risk solely based on tumor size, as it may present with asymptomatic and occult lymph node metastasis.