Papillary thyroid microcarcinoma: is active surveillance always enough?

The incidence of papillary thyroid carcinoma (PTC) has increased over recent decades. This apparent epidemic has been attributed to the overdiagnosis of small PTC ≤ 10mm in diameter (PTMC) incidentally detected on imaging for unrelated presentations. While most PTMC follow an indolent disease course, there is a small but significant proportion of cases that display more biologically aggressive features such as early metastasis and lymph node involvement. Management of PTMC diagnosed preoperatively should be distinguished from managing those PTMCs incidentally discovered after thyroidectomy. Here, we will focus on the challenge of managing the preoperative patient. Current guidelines recommend against routine biopsy of nodules ≤ 10mm even if they display highly suspicious features on ultrasound; however, it is not known how to identify those PTMC at higher risk of disease progression. In view of their good prognosis even without surgical resection, active surveillance has emerged as an alternative to operative management for low risk PTMC without lymph node involvement or distant metastasis. This review aims to summarise active surveillance data for PTMC and identify clinical features that may differentiate the indolent majority from those PTMC that exhibit early disease progression and metastasis. This article is protected by copyright. All rights reserved.