Active surveillance in low risk papillary thyroid carcinoma

Figure 4 Risk of cervical structure invasion related to tumor location (adapted from Miyauchi et al[40], 2018). Tumors composing obtuse angles with trachea, absence of normal thyroid tissue interposed between tumor and course of recurrent laryngeal nerve (RLN), and tumor location close to posterior thyroid capsule represent high risk features related to cervical structure invasion. References: A: Angles between tumor and tracheal surface: (1) Obtuse; (2) Acute; (3) Almost straight; B: Tumor location: (1) Central; (2) Anterior capsule; (3) Posterior capsule; C: Normal thyroid tissue in direction of RLN: (1) Present; (2) Absent.