肝脏炎性肌纤维母细胞瘤的CT、MRI表现及病理特征

Medical imaging findings and pathological characteristics of hepatic inflammatory myofibroblastic tumor

目的探讨肝脏炎性肌纤维母细胞瘤（HIMT）的CT和MRI表现与病理特征。方法回顾性分析3l例经手术病理证实的HIMT患者CT、MRI表现，观察肿瘤的部位、大小、形态、边缘、密度或信号、增强后强化方式。结果31例HIMT患者中，肿瘤位于肝右叶26例，肝左叶5例。位于肝包膜下27例。肿瘤单发28例，多发3例。肿瘤最大直径2．1～12．5ClTI，平均（3．6±1．2）cm。肿瘤呈类圆形或椭圆形21例，不规则形10例。CT检查（n=19）平扫均表现为低密度影，CT值5～35HU，平均（27．6±5．3）HU。肿瘤密度均匀6例，不均匀13例，其中3例肿瘤内呈蜂窝状改变。肿瘤界限清楚8例，不清楚11例。MRI检查（n=21）：肿瘤界限清楚8例，不清楚13例；肿瘤于T2wI上呈等信号12例，稍高信号9例，脂肪抑制序列均呈高信号。T，WI上均呈低信号；肿瘤信号均匀6例，不均匀15例，其中7例肿瘤内见蜂窝状改变和分隔。增强强化方式（31例）：全瘤填充型12例，边缘强化型9例，分隔强化型8例，无强化型2例。病理检查：镜下见增生的梭形细胞、慢性炎细胞（包括淋巴细胞、浆细胞）及胶原纤维形成，其中梭形细胞具有纤维母细胞和肌纤维母细胞特点。免疫组化检查23例，波型蛋白（Vimentin）均阳性，其中平滑肌肌动蛋白（SMA）阳性18例，肌特异性肌动蛋白（MSA）及结蛋白（Desmin）阳性12例，CD68阳性（＋）4例，ALK、S-100蛋白、CD117和CD35均为阴性。结论HIMT的CT与MRI平扫表现多样性。其强化方式有全瘤填充型、边缘强化型、分隔强化型、无强化型。强化特点为动脉期轻度至中度强化，门脉期进一步强化，延迟期持续轻度强化。

Objective To study the medical imaging findings and the pathological features of hepa- tic inflammatory myofibroblastic tumor （HIMT） using CT, MRI and histopathoiogy. Methods The CT and MRI findings of 31 patients with HIMT which were confirmed by histopathology on surgically resected speci- men were analyzed retrospectively. The location, size, shape, edge, density or signal, and contrast en- hancement of these tumors were analyzed. Results The tumors were located in the right liver in 26 pa- tients, in the left liver in 5 patients, and under the hepatic capsule in 27 patients. The tumors were solitary in 28 patients and mukiple in 3 patients. The maximum diameter of the tumor ranged from 2.1 cm to 12.5 cm. The average diameter was （3.6 -± 1.2） cm. The tumors were round or oval in 21 patients and irregular in 10 patients. 19 patients underwent CT examination and all tumors showed low density, with a CT value which ranged from 5 to 35HU. The average value was （27.6 ±5.3） HU. The density of tumors was homo- geneous in 6 patients and inhomogeneous in 13 patients, and among these 13 patients, 3 were alveolate. Twenty-one patients underwent MRI scan and all showed a low signal on T1WI, 12 patients showed an equal signal and 9 patients showed a slightly higher signal on T2WI. In 6 patients the signals were homogeneous and in 15 patients they were inhomogeneous. On CT and MRI enhanced scans the whole tumor was enhanced in 12 patients, the edge was enhanced in 9 patients, the septum was enhanced in 8 patients and no enhance- ment was observed in 2 patients. Pathological examination under microscopy observed the presence of prolif- eration of spindle cells, chronic inflammatory ceils which included the proliferation of lymphocytes, plasma cells and collagen fiber formation. The spindle cells had the characteristics of fibroblasts and myofibroblast cells. Immunohistochemical examination showed the wave type protein （Vimentin） was positive in 23 pa- tients, the smooth muscle actin （SMA） was positive in 18 patients, the muscle actin （MSA） and the specificity of junction protein （Desmin） were positive in 12 patients, CD68 was positive in 4 patients, and the ALK, S-100 protein, CD117 and CD35 were all negative. Conclusions The radiologicat features of CT and MRI plain scan varied. The patterns of contrast enhancement included full tumor filling, marginal enhancement, compartment enhancement, and no enhancement. The enhanced features varied from mild to moderate enhancement in the arterial phase, further enhancement in the portal phase and mild enhancement in the delayed phase.