甲状腺结节微波消融治疗后液化性坏死原因分析及处理

目的 探讨甲状腺结节微波消融治疗后消融区出现液化性坏死的可能原因及合适的处理方法。方法 对2008年1月至2017年12月接受微波消融治疗的3 480枚甲状腺结节进行随访,回顾性分析术后消融区液化性坏死患者的临床资料及处理方法与结果。结果 3 480枚甲状腺结节中,18枚（0.52%）微波消融术后消融区出现液化性坏死。18枚（100.00%）甲状腺结节术前最大长径均≥ 2.5 cm,位置均紧邻甲状腺包膜,术中均采用热阻断血流法,液化性坏死发生后外周血白细胞计数及比例均在正常范围。18例术后消融区发生液化性坏死的患者均临床痊愈,其中2例口服抗炎药即自行消散,消融区局部未作处理;10例行手术切开清除消融区液化性坏死物,14~26 d后切口愈合（2例颈部皮肤形成明显瘢痕）;6例行超声引导下扩开消融针穿刺窦道引流,10~20 d后液化坏死物消散,皮下窦道愈合,颈部均无瘢痕形成。16例患者行液化坏死物标本细菌培养,培养结果均为阴性。结论 微波消融治疗甲状腺结节术后消融区凝固性坏死组织液化是一种无菌性过程,可能与结节体积大、位置贴近包膜、热阻断血流有关,"液化与吸收失平衡"假说或许为探索其潜在机制提供线索;超声引导下扩开穿刺窦道可成功引流坏死物并避免颈部皮肤形成瘢痕。

Cause analysis and management of liquefactive necrosis of thyroid nodules after microwave ablation

Objective To explore the possible causes and the appropriate management of liquefactive necrosis in ablative area after microwave ablation for thyroid nodules. Methods A total of 3 480 thyroid nodules treated with microwave ablation between Jan. 2008 and Dec. 2017 were followed up. The clinical data, treatment methods and outcomes of the patients with liquefactive necrosis in ablative area were analyzed retrospectively. Results Of the 3 480 thyroid nodules, 18 (0.52%) had liquefactive necrosis in ablative area after microwave ablation. The maximum diameters of the 18 (100.00%) thyroid nodules were all greater than or equal to 2.5 cm before microwave ablation, the locations were all closely adjacent to the thyroid capsule, blood flows surrounding the nodules were all blocked by microwave energy during ablative operation, and the counts and proportions of white blood cell in the peripheral blood were all normal after the occurrence of liquefaction. Eighteen patients with liquefactive necrosis in ablative area were all clinically cured. In 2 cases among them, the necrosis dissipated spontaneously after orally taking anti-inflammatory drugs without local treatment for the ablation area. Ten patients underwent surgical incision to remove the liquefactive necrotic substance in the ablation area, and the incision healed on 14-26 days; and 2 cases in them had obvious scar formation on the neck skin. Six patients underwent ultrasound-guided drainage to remove the necrosis, the subcutaneous sinus tract healed on 10-20 days, and all had no neck scar formation. Bacterial culture of liquefactive material was performed in 16 patients, and the results were all negative. Conclusion The liquefaction of coagulated necrotic tissue in the ablative area of thyroid nodules after microwave ablation is a sterile process, and may be related to the large size of nodules, the close location of nodules to the capsule and the thermal blockade of blood flow. The "liquefaction and absorption disequilibrium" hypothesis may provide clues for exploring its potential mechanism. Ultrasound-guided drainage by dilating the subcutaneous sinus can successfully remove the necrotic materials and avoid scarring of neck skin.