Imaging features of solitary extramedullary plasmacytoma of liver

Abstract

Objective To summarize the imaging features of ultrasound, computed tomography (CT)and gadolinium-ethoxybenzyl-diethylenetriamine pentoacetic acid (Gd-EOB-DTPA)enhanced magnetic resonance imaging (MRI)of solitary extramedullary plasmacytoma (SEP)of liver, and investigate the key points of identification and diagnosis. Methods The clinical data of 1 patient with SEP of the liver who was admitted to the Southwest Hospital of the Third Military Medical University at 7 May, 2015 were retrospectively analyzed.The patient received contrast-enhanced ultrasound (CEUS), plain and enhanced scan of CT and Gd-EOB-DTPA enhanced MRI.The patient underwent treatment after preoperative examinations.Pathological examination and immunohistochemical staining were done after operation.The patient was followed up by outpatient examination of color Doppler ultrasonography till 12 November, 2015.The location, size, shape, echo, density or signal, enhancement pattern, secondary performance were recorded by imageological examinations.Surgical treatment, results of pathological examination, immunohistochemical staining, postoperative recovery and recurrence of tumor were recorded. Results CEUS examination demonstrated a hypoechoic hepatic lesion at S7 segment of the right liver measuring 24 mm × 19 mm with clear boundary and dotted blood flow signal in the mass.In the arterial phase, the lesion was enhanced rapidly.Abdominal CT scan showed that the mass at the right liver lobe had slightly low density with clear boundary, the CT value of 34-64 HU, and liver capsule having no significant outer convex.On enhanced CT, the lesion presented a homogeneous enhancement and shape of posterior upper tributaries of right hepatic artery in the arterial phase, the lesion presented continuous enhancement which was slightly lower than that of liver parenchyma in the portal venous phase with the CT value of 77 -102 HU, the lesion presented decreased enhancement with the CT value of 41-98 HU in the equilibrium phase.The maximum density projected image showed that the shape of an enlarged vascular image was found inside the lesion in the arterial phase and the lesion was adjacent to inferior vena cava and right hepatic vein which was compressed and displaced in the portal venous phase.On Gd-EOB-DTPA enhanced MRI, the right liver lobe showed a homogeneous T1-weighted and T2weighted signal with clear boundary and without lipid component, hemorrhage or calcification.The lesion presented obvious enhancement in the arterial phase, homogeneous continuous enhancement which was slightly lower than that of liver parenchyma in the portal venous phase, decreased enhancement in the equilibrium phase. The lesion showed mild signal, adjacent to inferior vena cava and right hepatic vein which was compressed and displaced in the hepatobiliary phase.There was no obvious cirrhotic nodule in the liver.The patient received laparoscopic space-occupying lesion resection at the right liver lobe after finishing inspection.The grayish white lesion in hardness was seen, with clear boundary and capsule, adjacent to anterior wall of inferior vena cava and right hepatic vein in the operation.The results of pathological examination showed that the small tumor cells were scattered in bundle, nuclear were round or oval shape and eccentric with mitosis seen.The results of immunohistochemical staining showed that endothelium cell marker CD34, human multiple myeloma gene MUM1, vimentin, plasmacyte markers 38 and 138, expression of λ light chain protein were positive, the positive cell rate of proliferation activity marker Ki-67 was 10%.The results of blood routine test and blood biochemistry showed that the patient had no anemia, hypercalcemia, abnormal renal function or monoclonal immunoglobulin in the serum or urine.The results of postoperative bone marrow aspiration, immunoglobulin determination and whole body bone scan showed normal.Postoperative examinations confirmed the SEP of right liver.The patient recovered well and was discharged at postoperative day 9.Postoperative change at right liver lobe was detected by color Doppler ultrasonography at 1 month after operation.The patient was followed up for 6 months without tumor recurrence. Conclusion SEP of liver mainly locates at the right lobe of liver, and the imaging features include clear boundary, homogeneous echo, density or signal, adjacent capsule showing no significantly outer convex, surrounding vein demonstrating no violation and shifted by compression ,enhancement pattern as fast-in and fast-out. Key words: Liver neoplasms; Extramedullary plasmacytoma; Tomography, X-ray computed; Magnetic resonance imaging; Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid