纵隔型支气管源性囊肿影像特征及误诊报告

目的探讨纵隔型支气管源性囊肿(mediastinal bronchogenic cyst,MBC)影像特征及误诊原因。方法对经手术及病理检查证实的18例MBC的临床及影像资料进行回顾性分析。结果18例中行CT平扫加增强扫描4例,仅行CT平扫1例,行CT平扫加增强扫描及MRI平扫1例;余12例均行CT增强扫描。18例影像学检查囊肿大小不一,均为单发,以类圆形、椭圆形为主;2例为水样密度型,16例为软组织密度型;17例CT增强扫描示8例未强化,4例为轻度均匀强化,3例为中度均匀强化,1例为轻中度强化,1例为囊内未强化而囊壁强化。1例行MRI检查表现为T1WI呈低信号,T2WI呈高信号,压脂序列呈高信号。18例术前确诊3例,误诊15例,误诊率83.33%;位于前纵隔者误诊为胸腺瘤6例,淋巴结增大和良性病变各2例,胸腺囊肿1例;中纵隔者报告为良性病变1例;后纵隔者误诊为神经源性肿瘤、淋巴管瘤和良性病变各1例;误诊时间2个月~1年。18例均于胸腔镜下行囊肿切除术,皆经术后病理检查确诊MBC,术后均予常规治疗。随访1~6个月,18例皆无复发,预后较好。结论MBC具有一定影像特征,CT是其首选检查方法,增强CT检查有助于定位、定性诊断,MRI是其补充检查手段,但确诊需依赖术后病理检查。MBC术前误诊可能与发病率较低、接诊医师对该病认识不足、临床表现无特异性、影像扫描方案不完善及囊肿成分复杂等有关。

Imaging Features and Misdiagnosis of Mediastinal Bronchogenic Cyst

Objective To investigate the imaging features and causes of the misdiagnosis of mediastinal bronchogenic cyst(MBC).Methods The clinical and imaging data of 18 patients with MBC confirmed by operation and pathology were retrospectively analyzed.Results Of the 18 MBC cases,4 cases received CT plain scan and enhanced scan,only 1 case received CT plain scan,and 1 case received CT plain scan,enhanced scan and MRI plain scan.The remaining 12 cases received enhanced CT scan.The size of MBC varied in 18 cases based on imaging examination,all of them were single,mainly round and oval.Two cases were water sample density type,and 16 cases were soft tissue density type.In 17 cases receiving enhanced CT scan,8 cases showed no enhancement,4 cases showed mild homogeneous enhancement,3 cases showed moderate homogeneous enhancement,1 case showed mild moderate enhancement,and 1 case showed no enhancement in the capsule but enhancement in the capsule wall.According to MRI results,1 case showed hypointensity on T1WI,hyperintense on T2WI and hyperintense on lipidomic sequence.In 18 cases of MBC,3 cases were correctly diagnosed and 15 cases were misdiagnosed.The misdiagnosis rate was 83.33%.For those with MBC at anterior mediastinum,6 cases were misdiagnosed as thymoma,2 cases with enlarged lymph nodes,2 cases with benign signs,and 1 case with thymic cyst.For those at middle mediastinum,1 case was misdiagnosed with benign lesion.For those at posterior mediastinum,1 case was misdiagnosed with neurogenic tumor,1 case with lymphangioma and 1 case with benign lesion.The duration of misdiagnosis was 2 months to 1 year.All the 18 cases underwent thoracoscopic cystectomy and were diagnosed as MBC by postoperative pathological examination.All received conventional treatment after operation,and there was no recurrence during the follow-up from 1 month to 6 months.No recurrence was reported in 18 cases and the prognosis was favorable.Conclusion MBC has typical imaging features,therefore,CT is preferred imaging method for diagnosis.Enhanced CT examination is helpful for localization and qualitative diagnosis,and MRI is its supplementary examination method,however,the diagnosis depends on postoperative pathological examination.The preoperative misdiagnosis for MBC may be related to the low incidence,insufficient knowledge of the disease of clinicians,non-specific clinical manifestations,imperfect imaging scan plan,and complex cyst components.