PMC9875614_01
Findings of enhanced abdominal computed tomography (CT) and F-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT: Abdominal CT showing a hepatic mass with early enhancement of the peripheral areas in the arterial phase (A, B) and low-density structures within the tumor in the delayed phase (C, D). FDG-PET/CT revealing heterogeneous uptake in the tumor (E, F).
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Examination using contrast-enhanced CT confirmed the presence of a mass (diameter: 5.0 cm) in the hepatic segment 5, characterized by early enhancement of the peripheral area in the arterial phase (Figure 1A, B) and slight internal heterogeneous enhancement in the delayed phases (Figure 1C, D).
Results of magnetic resonance imaging: Tumor showing low and high signal intensity on T1-weighted images (A) and T2-weighted images (B), respectively. Diffusion-weighted images revealing high signal intensity in the central part of the tumor, corresponding to the low-density area detected through enhanced computed tomography (C).
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Diffusion-weighted imaging also showed high intensity in the corresponding low-density area detected using CT (Figure 2).
Macroscopic and microscopic features of the resected tumor: CT features of an anterior sector of the liver including the tumor (A). The blue broken line indicates the dividing line used during surgery, and the red broken line shows the cutting line in the resected specimen. Resected specimen (B: above is the head side). The cut surface divided along the red broken line reveals two distinct intermingled components: a whitish area (within the white broken line: NEC area) and a yellowish area (within the blue broken line: HCC area) (C). The horizontal cut surface along the black broken line (C) also shows two distinct components (D).
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In the tumor, two distinct components intermingled with the transitional area and the surrounding tissue was indicative of chronic hepatitis without signs of cirrhosis (Figure 3).
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Histological characteristics: The hepatocellular carcinoma-dominant area is shown inside the blue broken line (A; stain, hematoxylin and eosin stain, magnification, x200) and the neuroendocrine carcinoma-dominant area inside the white broken line (B; stain, hematoxylin and eosin stain, magnification, x400) with transitional area (C; stain, hematoxylin and eosin stain, magnification, x20).
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These histological features indicated moderately differentiated HCC (Figure 4A). In contrast, gross examination revealed a sheet-like arrangement of atypical cells in the white-to-gray component with a high nucleus-to-cytoplasm ratio and chromatin (Figure 4B). Atypical cells with enlarged nuclei and a relatively broad cytoplasm were detected in the region between the two components, potentially constituting a transitional area (Figure 4C).
Immunostaining: The neuroendocrine carcinoma component was positive for synaptophysin (A; magnification, x100) and chromogranin A (B; magnification, x100), and the Ki-67 labeling index was approximately 35% (C; magnification, x400).
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Furthermore, we determined the Ki-67 labeling index (~35%) (Figure 5).
Comparison of findings of PET-CT with dynamic MRI and enhanced CT. FDG-PET/CT revealed a strong uptake in the corresponding NEC area in the tumor detected from dynamic MRI and enhanced CT, respectively.
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Retrospectively, the findings of PET-CT are compared with those of dynamic MRI (Axial view) and enhanced CT (Coronal view), respectively (Figure 6).