Synchronous occurrence of papillary thyroid microcarcinoma, medullary thyroid carcinoma and Hashimoto thyroiditis in a single thyroid: A case report with literature review

INTRODUCTION: The synchronous development of a medullary and papillary carcinoma as two different tumors has only been reported very rarely. The aim of the current report is to describe an extremely rare occurrence of medullary carcinoma, papillary microcarcinoma, and Hashimoto thyroiditis. CASE REPORT: A 53-year-old man presented with a right-sided neck mass. Ultrasound showed a well-defined nodule in the right mid third with microcalcification and increased nodular vascularity associated with multiple right-sided cervical lymphadenopathy. The histopathological examination showed multifocal medullary carcinoma with incidental finding of unifocal papillary microcarcinoma conventional type on the left side. Additional pathology of Hashimoto thyroiditis with a small intra-thyroidal parathyroid gland in the left thyroid gland. The procedure went perfectly and the patient was discharged home without any difficulties. DISCUSSION: Synchronous existence of these two neoplasms can occur in two forms: distinct medullary carcinoma and papillary carcinoma isolated by normal thyroid tissue, or mixed medullary and follicular-derived thyroid carcinoma, in which single or multiple lesions show morphology and immunoreactivity for both medullary carcinoma and follicular-derived carcinoma. CONCLUSION: The synchronous coexistence of papillary microcarcinoma, medullary carcinoma, and Hashimoto's thyroiditis is an uncommon thyroid condition.