Medical imaging findings and pathological characteristics of hepatic inflammatory myofibroblastic tumor / 中华肝胆外科杂志

ABSTRACT

Objective To study the medical imaging findings and the pathological features of hepatic inflammatory myofibroblastic tumor (HIMT) using CT,MRI and histopathology.Methods The CT and MRI findings of 31 patients with HIMT which were confirmed by histopathology on surgically resected specimen were analyzed retrospectively.The location,size,shape,edge,density or signal,and contrast enhancement of these tumors were analyzed.Results The tumors were located in the right liver in 26 patients,in the left liver in 5 patients,and under the hepatic capsule in 27 patients.The tumors were solitary in 28 patients and multiple 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 homogeneous 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 enhancement was observed in 2 patients.Pathological examination under microscopy observed the presence of proliferation of spindle cells,chronic inflammatory cells 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 patients,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,CDll7 and CD35 were all negative.Conclusions The radiological 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.