Application of thermal ablation therapy by using microwave or radiofrequency energy for benign thyroid nodules or/ and thyroid malignancies gets increased world-wide. Potential risks involved in the ablation procedure are not uncommon and could be catastrophic when out of control. Ablation for pharyngeal esophageal diverticulum's (PED) being misdiagnosed as thyroid nodules constitutes the risks. In this case report, the authors presented another potential threat to such ablation treatment, which derived from a trachea diverticulum complicated with inflammatory hyperplastic tissue by misdiagnosis as thyroid nodules. The tracheal diverticulum (TD) reported in this study was interpreted as a calcified thyroid nodule on ultrasonography at first, then microwave ablation (MWA) was accordingly recommended as one of the therapeutic options. However, the first author, experienced with the ultrasonic features of PED, insisted the differential diagnosis should be made between nodule and PED. Subsequently, swallow contrast-enhanced ultrasonography (CEUS) and barium meal test were carried out successively, but neither of them reported the presence of PED. Percutaneous fine-needle aspiration (FNA) was hence operated to identify pathological characteristics of the "calcified thyroid nodule", and cytological tests under microscopy indicated the nodule originated from trachea due to the presence of ciliated columnar epithelial cells with inflammatory exudates within the specimen.Cervical and thoracic X-ray CT examination was further conducted, and a TD was discovered. The case was finally concluded as a TD with inflammatory hyperplastic tissue. The value of this case lies in that once a TD was misdiagnosed as ablation-candidate thyroid nodule in conventional ultrasonography could cause the latent danger to thyroid thermal therapy. Rigorous and effective differential diagnosis prior to thermal ablation procedure could prevent misdiagnosis and mistreatment.

With the increasingly used semi-thyroidectomy and rapid progress in ultrasound-guided thermal ablation therapy for treatment of papillary thyroid carcinoma (PTC) and cervical lymph node metastasis from PTC, ultrasound-guided fine needle aspiration biopsy (FNAB) has got the mainstream position in pre-treatment cytopathologic diagnosis of PTC. How to acquire adequate and qualified cellular specimen for cytological examination has been described in several published expert consensus and practice guidelines. However, new issues continue to emerge in the real world of thyroid FNAB practice, and most of them are rooted in the perception and skills of the physician or technician who conduct FNAB. In this chapter, a series of new concept, idea, and technical methods are to be introduced and discussed. We believe that properly addressing these issues will facilitate the better implementation of FNAB and promote the new therapeutic modalities such as the thermal ablation to better progress.

Lymphatic vessels are the only pathway for lymphatic fluid to flow into venous bloodstream, and they are also one of the main channels for migration and metastasis of malignant tumor cells. High-frequency ultrasound imaging has been used popularly as first choice for examination and preliminary assessment of cervical lymph nodes. However, its capacity of displaying lymphatic vessels is still insufficient up to date. Recently, liquid isolation has been increasingly used in ultrasoundguided thermal ablation treatment of thyroid nodules, parathyroid nodules, or cervical lymph nodes with malignant metastasis, playing a key role of protecting adjacent surrounding structures. In this paper, the role of liquid isolation in optimizing the ultrasonic display of cervical lymphatic vessels was presented and further likely novel technique based on this case was outlook as well.