PMC6378515_01
The imaging, gross, microscopic, and immunohistochemical examinations of the hepatic IMT. (A) Abdominal dynamic CT shows an unenhanced and low-density, heterogeneous and increasing mass (arrows) in the peripheral right lobe of the liver. (B) The cut surface of the hepatic IMT case characteristically demonstrates a relatively well-demarcated and partly infiltrative and likely extrahepatic (ie serosal) but not intrahepatic mass, measuring 51 x 32 mm in diameter, which appears firm and hemorrhagic and yellow-whitish in color. The background of this liver reveals no remarkable change (bar = 1 cm). (C) A microscopic examination of the hepatic IMT case (H&E staining) also shows an unencapsulated, partly ill-defined and expansive or infiltrative mass, potentially growing from the extrahepatic, serosal side. (D) On a low-power view (H&E staining), this mass reveals a solid proliferation of myofibroblast- or fibroblast-like spindled to oval cells, arranged in fascicles in a small amount of collagenous stroma, admixed with many inflammatory cells including lymphocytes, plasma cells, histiocytes, neutrophils, and eosinophils. (E) On a high-power view, these tumor cells are mildly atypical, having enlarged hyperchromatic nuclei, prominent nucleoli, and rare mitotic figures. (F) Immunohistochemistry demonstrates that those mildly atypical tumor cells are specifically positive for alpha-SMA (left) and cytokeratins including AE1/AE3 (right).
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The patient, who was a woman in her early 70s with an unremarkable previous medical history, except for 2-year follow-up against lung cryptococcosis and traffic accident, incidentally presented with unenhanced and low-density, heterogeneous and increasing mass on abdominal dynamic computed tomography (CT) in the peripheral right lobe of the liver (Figure 1A). The image in coregistered 2-deoxy-2-[18F]fluoro-d-glucose (18F-FDG PET)/CT showed a large and overtly hypermetabolic area in the peripheral right lobe of the liver (maximal standardized uptake value [SUV]: 8.17), which corresponded to a unenhanced and low-density, heterogeneous and increasing mass on abdominal CT (Figure 1C). On gross examination, the cut surface of right hepatic mass (Figure 1B) demonstrated a relatively well-demarcated and partly infiltrative and likely extrahepatic (ie serosal) but not intrahepatic mass, measuring 51 x 32 mm in diameter, which appeared firm and hemorrhagic and yellow-whitish in color. The background of this liver revealed no remarkable change (Figure 1B). A microscopic examination of the tumor showed an unencapsulated, partly ill-defined and expansive or infiltrative mass (Figure 1C), potentially growing from the extrahepatic, serosal side. On a low-power view, this cancerous mass revealed a solid proliferation of myofibroblast- or fibroblast-like spindled to oval cells, arranged in fascicles in a small amount of collagenous stroma, admixed with many inflammatory cells including lymphocytes, plasma cells, histiocytes, neutrophils, and eosinophils (Figure 1D). On a high-power view, these tumor cells were mildly atypical, having enlarged hyperchromatic nuclei, prominent nucleoli, and rare mitotic figures (Figure 1E).