肾上腺神经鞘瘤的CT诊断

CT Diagnosis of Adrenal Schwannoma

目的肾上腺神经鞘瘤少见。本文分析肾上腺神经鞘瘤的CT表现,以提高对本病的认识及诊断水平。资料与方法回顾性分析经手术及病理证实为肾上腺神经鞘瘤的6例患者的CT影像资料。结果 4例肿瘤位于右侧肾上腺,2例位于左侧肾上腺。肿瘤直径为3.0-6.4 cm,平均（4.5±1.3）cm,边界均清楚锐利。肿瘤平扫密度均与肾脏密度相仿或稍低,平均CT值为（32±7）HU,3例密度均匀,3例内部片状稍低密度影。增强扫描后6例肿瘤均轻、中度强化,并呈缓慢逐渐强化模式。动脉期呈轻度均匀或絮状强化,静脉期及延迟期强化程度均有增加,动脉期、静脉期及延迟期CT值平均增加（13±2）HU、（18±4）HU及（23±4）HU。1例肿瘤内部见无强化的斑片状囊变区。结论肾上腺神经鞘瘤CT表现为相对均质的肿块,增强扫描后的轻中度强化及逐渐缓慢强化模式可能是肾上腺神经鞘瘤特征性的CT征象。

Purpose Adrenal schwannoma is rare and quite difficult to diagnose before operation. This paper aims to analyze the CT findings of adrenal schwannoma to improve the recognition and diagnosis of this disease. Materials and Methods The CT findings of 6 patients with adrenal schwannomas proved by operation and pathology were retrospectively analyzed. Results Four schwannomas were located in the right adrenal and 2 in the left adrenal. The tumors, with diameters ranging from 3.0 cm to 6.4 cm, mean（4.5±1.3） cm, had well-defined margin. The densities of all the masses were close to or slightly lower than those of kidneys on plain scan images, with mean CT attenuation value of（32±7） HU. Three masses showed homogeneous density and the other 3 were mildly heterogeneous with patches of lower density. All the 6 schwannomas were enhanced mildly or moderately after intravenous administration of contrast material and showed gradual enhancement mode. They showed mild homogeneous or flocculent enhancement on arterial phase and had gradual progress on venous and delayed phases. The mean increase of CT attenuation value was（13±2） HU on arterial phase,（18±4） HU on venous phase and（23±4） HU on delayed phase. Only 1 mass showed some patches of cystic degeneration without enhancement inside. Conclusion Adrenal schwannoma should be included in the differential diagnosis of solid nonfunctioning adrenal tumors. Features such as relatively homogeneous mass, mild to moderate enhancement and gradual enhancement mode after contrast enhancement are possibly the unique CT manifestations of adrenal schwannoma.