Simultaneous Occurrence of Different Follicular Neoplasms within the Same Thyroid Gland

ABSTRACT

Purpose: Neoplasms of the thyroid gland are classified according to the cells they originate from and commonly develop from cells of follicular origin. The most common differentiated thyroid cancers (DTC) are papillary and follicular carcinomas. Coexistence of two different histological types of primary follicular thyroid neoplasm is a rare condition. There are previous reports of concomitant medullary and papillary thyroid cancers. However, there is scarce data about the simultaneous occurrence of the two different histological types of primary follicular thyroid tumors and this is the first study on that subject.
Material and Method: From January 2007 to September 2014, our institutional database was reviewed for patients who underwent thyroid surgery for various indications. Medical records and cytopathology reports of those patients were examined retrospectively. Simultaneous neoplasms of follicular origin were noted.
Results: A total of 3.700 patients were operated. Histopathological examination revealed a benign pattern in 2.686 (73%) patients and a malignant pattern in 1.014 (27%) patients. Among the patients with the diagnosis of DTC, only 20 (1.9%) had a concomitant neoplasm within the same thyroid gland.
Discussion: Such simultaneous tumors may be a part of a familial tumor syndrome or an unidentified novel gene mutation playing role in the pathogenesis of more than one type of tumor. Based on the current evidence, the synchronous occurrence of those neoplasms in a given patient is likely coincidental in the literature. Further studies on larger patient population with standardized genetic characterization are needed.