Synchronous occurrence of papillary thyroid carcinoma and medullary thyroid carcinoma in the setting of Hashimoto's thyroiditis: a case report with literature review.

Abstract

Background: The incidence of medullary thyroid carcinoma (MTC) originating from parafollicular cells of the thyroid gland is relatively low among all thyroid cancers, and MTC combined with papillary thyroid carcinoma (PTC) is even rarer. In this article, we report a case of MTC combined with PTC on the background of Hashimoto's thyroiditis (HT) and discuss several points surrounding the diagnosis and management.

Case description: A 59-year-old woman was admitted to the hospital with the main cause of "right neck pain for 6 months and right thyroid nodules for 20 days". Ultrasound showed multiple Thyroid Imaging-Reporting and Data System (TI-RADS) grade 3 hypoechoic nodules in the right lobe, and a hypoechoic nodule in the proximal isthmus of the right lobe, with a poorly defined border and TI-RADS grade 4a. No obvious enlarged lymph nodes were seen in the anterior neck. Preoperative calcitonin (Ctn) was found to be 614.9 pg/mL (normal range, 0.00-6.40 pg/mL). Postoperative histopathologic findings returned: papillary carcinoma of the right thyroid gland, invading the peritoneum of the thyroid gland, and another more diffuse growth nodule was seen, which was consistent with medullary carcinoma of the thyroid gland; with a background of HT. The patient was successfully discharged from the hospital after surgical treatment.

Conclusions: HT with PTC and MTC is an extremely rare disease. By reporting the diagnosis and treatment of this case, this article can provide experience for subsequent clinical studies.