Imaging findings of primary gastric plasmacytoma:A case report

Primary gastric plasmacytoma(GP)is a rare extramedullary plasmacytoma with clinical and imaging features that are common among other gastric tumors,such as gastric adenocarcinomas,gastric stromal tumors,and lymphomas.Here,we present a histologically confirmed case of primary GP examined with biphasic computed tomography(CT),magnetic resonance imaging(MRI),and endosonography.A well-circumscribed extraluminal mass appearing as homogeneous attenuation/intensity with gradual enhancement was identified on biphasic enhancement CT and MRI.This mass was hyperintense on diffusion-weighted imaging and hypointense on the apparent diffusion coefficient map,implying that water diffusion in the mass was restricted.In addition,endosonography indicated a low echogenic mass in the gastric wall.These imaging findings increase the available knowledge about imaging of this disease and provide valuable information for differentiating primary GP from common gastric tumors.

Dual-input two-compartment pharmacokinetic model of dynamic contrast-enhanced magnetic resonance imaging in hepatocellular carcinoma

AIM: To investigate the feasibility of a dual-input two-compartment tracer kinetic model for evaluating tumorous microvascular properties in advanced hepatocellular carcinoma(HCC). METHODS: From January 2014 to April 2015, we prospectively measured and analyzed pharmacokinetic parameters [transfer constant(K_(trans)), plasma flow(F_p), permeability surface area product(PS), efflux rate constant(k_(ep)), extravascular extracellular space volume ratio(V_e), blood plasma volume ratio(V_p), and hepatic perfusion index(HPI)] using dual-input two-compartment tracer kinetic models [a dual-input extended Tofts model and a dual-input 2-compartment exchange model(2CXM)] in 28 consecutive HCC patients. A well-known consensus that HCC is a hypervascular tumor supplied by the hepatic artery and the portal vein was used as a reference standard. A paired Student's t-test and a nonparametric paired Wilcoxon rank sum test were used to compare the equivalent pharmacokinetic parameters derived from the two models, and Pearson correlation analysis was also applied to observe the correlations among all equivalent parameters. The tumor size and pharmacokinetic parameters were tested by Pearson correlation analysis, while correlations among stage, tumor size and all pharmacokinetic parameters were assessed by Spearman correlation analysis. RESULTS: The F_p value was greater than the PS value(F_P = 1.07 m L/m L per minute, PS = 0.19 m L/m L per minute) in the dual-input 2CXM; HPI was 0.66 and 0.63 in the dual-input extended Tofts model and the dualinput 2CXM, respectively. There were no significant differences in the K_(ep), V_p, or HPI between the dual-input extended Tofts model and the dual-input 2CXM(P = 0.524, 0.569, and 0.622, respectively). All equivalent pharmacokinetic parameters, except for V_e, were correlated in the two dual-input two-compartment pharmacokinetic models; both Fp and PS in the dualinput 2CXM were correlated with K_(trans) derived from the dual-input extended Tofts model(P = 0.002, r = 0.566; P = 0.002, r = 0.570); K_(ep), V_p, and HPI between the two kinetic models were positively correlated(P = 0.001, r = 0.594; P = 0.0001, r = 0.686; P = 0.04, r = 0.391, respectively). In the dual input extended Tofts model, V_e was significantly less than that in the dual input 2CXM(P = 0.004), and no significant correlation was seen between the two tracer kinetic models(P = 0.156, r = 0.276). Neither tumor size nor tumor stage was significantly correlated with any of the pharmacokinetic parameters obtained from the two models(P > 0.05).CONCLUSION: A dual-input two-compartment pharmacokinetic model(a dual-input extended Tofts model and a dual-input 2CXM) can be used in assessing the microvascular physiopathological properties before the treatment of advanced HCC. The dual-input extended Tofts model may be more stable in measuring the V_e; however, the dual-input 2CXM may be more detailed and accurate in measuring microvascular permeability.

Primary histiocytic sarcoma of the stomach:A case report with imaging findings

Histiocytic sarcoma(HS)is a rare malignant neoplasm that originates from a histiocytic hematopoietic lineage characterized by histiocytic differentiation and its corresponding immunophenotypic features.We herein reported a case of primary HS of the stomach which was confirmed through histopathologic examination and immunohistochemical staining.A 52-year-old woman presented with progressive difficulty in feeding and dull pain in the epigastric region.Gastroscopy,endo-scopic ultrasonography,double contrast examination, and computed tomography revealed a mass located on the posterior wall of fundus and lesser curvature of the stomach.Microscopically,the cytoplasm of the tumor cells was abundant and eosinophilic.Immunohisto-chemical staining revealed that the tumor cells were positive for CD45RO and CD68.It is difficult to differentiate HS of stomach from other gastric malignancies by radiological evaluation alone.However,HS may be considered when a protruding and ulcerated mass in stomach shows heterogeneous hypervascular features.To the best of our knowledge,this is the first report in English language literature that emphasizes the imaging findings of human gastric HS.