1. Conservative Surveillance Management of Low-Risk Papillary Thyroid Microcarcinoma 
Akira Miyauchi, MD, PhD, Yasuhiro Ito, MD, PhD 
Endocrinology and Metabolism Clinics 
Volume 48, Issue 1, Pages (March 2019)
DOI: /j.ecl
Copyright © 2018 The Author(s) Terms and Conditions

2. Fig. 1
The types of angles formed between the tumor surface and tracheal cartilage are related to the risk of tracheal invasion: (A) obtuse angle, (B) near-right angle, and (C) acute angle.
Endocrinology and Metabolism Clinics  , DOI: ( /j.ecl )
Copyright © 2018 The Author(s) Terms and Conditions

3. Fig. 2
(A) Upper two; A typical example of PTMC forming an obtuse angle (right, ultrasonography; left, computed tomography scan). This case required resection of the tracheal cartilage. (B) Lower two; A typical example of a PTMC forming an acute angle. (Ultrasonography; right, sagittal scan. Head to the left; left, transverse scan). This tumor was excised according to the patients’ wishes. There was no tracheal invasion.
Endocrinology and Metabolism Clinics  , DOI: ( /j.ecl )
Copyright © 2018 The Author(s) Terms and Conditions

4. Fig. 3
The presence (A) or absence (B) of a normal tissue rim in the direction of the recurrent laryngeal nerve is related to the risk of invasion to the nerve.
Endocrinology and Metabolism Clinics  , DOI: ( /j.ecl )
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5. Fig. 4
(A) Ultrasonography showing a hypoechoic mass lesion extending from the dorsal surface of the left thyroid lobe in a patient presenting with left vocal cord paralysis. (B) A computed tomography scan of the same patient revealing a low-density mass without a normal tissue rim in the direction of the left recurrent laryngeal nerve. Arrows indicate a tumor extending from the dorsal surface of the thyroid lobe.
Endocrinology and Metabolism Clinics  , DOI: ( /j.ecl )
Copyright © 2018 The Author(s) Terms and Conditions

6. Fig. 5
(A) Tumor located within a thyroid lobe is an ideal tumor for active surveillance. Tumors located at the anterior (B) and lateral (C) capsules of the thyroid lobe, with possible minimal extrathyroid extension, are not ideal for active surveillance but are nevertheless included in such surveillance.
Endocrinology and Metabolism Clinics  , DOI: ( /j.ecl )
Copyright © 2018 The Author(s) Terms and Conditions