Borderline Thyroid Tumors: a Surgeon's Perspectives

ABSTRACT

Borderline thyroid tumors are composed of hyalinizing trabecular tumor (HTT), well differentiated tumor of uncertain malignant potential (WDT-UMP), follicular tumor of uncertain malignant potential (FT-UMP) and non-invasive follicular tumor with papillary like nuclear feature (NIFTP) by World Health Organization (WHO) definition. They have different pathological feature from each other. However, it is difficult to diagnose with diagnostic imaging, fine needle aspiration (FNA) or core biopsy preoperatively. Thus, the diagnosis is usually made after diagnostic lobectomy. Main surgical concerns about borderline tumor are not performing total thyroidectomy because of relatively indolent nature of these tumors. Unfortunately, some of these tumors can be diagnosed as malignant tumor preoperatively. The other surgical concern is performing completion thyroidectomy or not after diagnostic lobectomy. Decision making is difficult even though it is generally considered that lobectomy alone is enough. In this article, we will discuss clinical features of borderline malignant tumors and surgical strategy for these tumors.