Pregnancy exacerbated lymph node metastasis of well differentiated thyroid carcinoma: A case report

INTRODUCTION: Differentiated thyroid carcinoma is the second most frequently diagnosed cancer during pregnancy, second to breast cancer. Pregnancy can cause an increase in the size of existing thyroid nodules due to the similar structure of placental human chorionic gonadotropin and thyroid stimulating hormone. However, the impact of pregnancy on malignant thyroid tumors is still unclear. PATIENT CONCERNS: We report a 27-year-old woman with initial thyroid follicular carcinoma was managed with total thyroidectomy and radioiodine therapy. Tumor recurrences with right neck lymph node enlargement were noted during the first and third trimester of pregnancy two years after initial diagnosis. DIAGNOSIS: Right neck lymph node dissection was performed for two episodes of recurrence and the pathology revealed both metastatic papillary thyroid carcinoma, follicular variant but with different pathologic features. And next-generation DNA sequencing of 275 cancer-related genes, which was a commercial set, including common mutations in thyroid cancer revealed only point mutations with unknown clinical correlation. INTERVENTION: For the first recurrence during pregnancy, right neck lymph node dissection was performed at the second trimester of pregnancy. As for the second recurrence in the third trimester of pregnancy, the patient received right neck lymph node dissection with radioiodine therapy one month after uncomplicated delivery. OUTCOMES: After complete treatment with surgery and radioiodine therapy, the serum thyroglobulin level was 10 ng/ml. During two-year regular follow-ups with serum thyroglobulin and ultrasound, no more recurrence was noted. CONCLUSION: Pregnancy in differentiated thyroid cancer survivors should be managed and monitored with caution, especially when cancer recurrence is noticed. Further studies are recommended to investigate these previously unreported gene mutations associated with thyroid cancer.