Primary hepatic benign schwannoma

Figure 1 Abdominal ultrasonography. Abdominal ultrasonography showed 24-mm diameter mixed echo pattern of iso- and hypoechoic mass without hallo in S2 of the liver, the findings of which were not typical for hepatocellular carcinoma or metastatic tumor.

Figure 2 Abdominal computed tomography. A: Unenhanced computed tomography (CT) scan showed a well-demarcated 2 cm-diameter lesion (arrow) in segment 2 of the liver on plain scan; B: Contrast-enhanced CT scan detected a ring-enhanced nodule (arrow) in the early arterial phase; C, D: wash-out pattern in the portal and equilibrium phase (arrows).

Figure 3 Magnetic resonance imaging. Magnetic resonance imaging showed a 2 cm tumor (arrows) in segment 2 of the liver. A: Low signal intensity in T1-weighted axial imaging; B, C: High signal intensity in T2-weighted; D: Diffusion-weighted axial imaging.

Figure 4 Fluorodeoxyglucose-positron emission tomography examination. In a fluorodeoxyglucose-positron emission tomography examination integrated with computed tomography scanning, the tumor did not show significant fluorodeoxyglucose uptake.

Figure 5 Macroscopic appearance of the lesion. Macroscopically, the resected specimen showed a tumor of 23 mm in diameter. The cut section showed a solid component. The tumor had no cystic component and lacked apparent capsule.

Figure 6 Microscopic appearance of the lesion. A: Histological examination revealed a tumor without fibrous capsule with interlacing bands of uniform spindle cells whose elongated nuclei were arranged in a palisading pattern (hematoxylin-eosin, original magnification × 200); B: Border area between tumor and non-tumor; C-E: Immunohistochemical analysis revealed that tumor cells were diffusely and strongly positive for S-100 (C), but negative for c-kit (D), or CD34 (E); F: The Ki-67 labeling index was 2%.