PDF(Pubmed)
Abstract：
A 53-year-old female with primary biliary cholangitis was referred for the evaluation of a hepatic nodule identified during routine imaging. Ultrasonography revealed a homogeneous, hypoechoic, 18 mm nodule in segment 3 of the liver. On dynamic CT and MRI, the nodule showed mild enhancement at the hepatic artery-dominant phase. On diffusion-weighted images, the nodule exhibited pronounced hyperintensity with accompanying wedge-shaped perinodular hyperintensity (comet and comet-tail appearance). The nodule showed a portal perfusion defect on CT during arterial portography, and mild enhancement on CT during hepatic arteriography (CTHA). A nodular and wedge-shaped perinodular enhancement (comet and comet-tail appearance) in the CTHA was also clearly observed. The nodule demonstrated abnormal FDG uptake on 18F-FDG-PET/CT. An excisional biopsy was performed for histopathological diagnosis, and the nodule was diagnosed as reactive lymphoid hyperplasia (RLH). Diagnosing hepatic RLH by imaging is challenging due to its imaging findings overlapping with those of various malignant tumors, especially the nodular type of lymphomas, making differentiation particularly difficult. However, radiologists should note the perinodular early enhancement and the perinodular hyperintensity on diffusion weighted images, which are thought to be key imaging findings of RLH, along with other characteristics such as a single, small, homogeneous nodule with mild early enhancement and marked restricted diffusion. We propose to name the nodular lesion with perinodular early enhancement/hyperintensity on diffusion weighted images as \'comet and comet-tail appearances\'.
摘要：
一名53岁的原发性胆汁性胆管炎女性被转诊，以评估在常规成像过程中发现的肝结节。超声检查显示均匀，低回声,肝脏3段18毫米结节。在动态CT和MRI上，结节在肝动脉优势期显示轻度增强。在扩散加权图像上，结节表现出明显的高强度，并伴随着楔形的结周高强度（彗星和彗星尾外观）。结节在动脉门静脉造影时CT显示门静脉灌注缺损，肝动脉造影（CTHA）时CT轻度增强。还清楚地观察到CTHA中的结节状和楔形的周波增强（彗星和彗星尾外观）。结节在18F-FDG-PET/CT上表现出异常的FDG摄取。进行了切除活检以进行组织病理学诊断，结节诊断为反应性淋巴增生（RLH）。通过影像学诊断肝脏RLH具有挑战性，因为其影像学表现与各种恶性肿瘤重叠，尤其是结节型淋巴瘤,使分化变得特别困难。然而,放射科医生应该注意到扩散加权图像上的周波早期增强和周波高强度，这被认为是RLH的关键影像学发现，以及其他特征，如单一，小,同质结节，轻度早期增强，扩散明显受限。我们建议在扩散加权图像上将结节性病变称为“彗星和彗星尾外观”。
