Malignant sarcomatoid tumor of the liver: report of a case.

A 65-year-old man was referred to our hospital for treatment of a liver tumor. Abdominal ultrasonography (US) demonstrated a low echoic mass in the S2-S4 region of the liver, which was confirmed by abdominal computed tomography (CT). In the delayed phase of angio-CT, the inside of the mass was not enhanced. Abdominal angiography showed a hypovascular area in the liver. An extended left lobectomy was performed. Macroscopically, the tumor was 9.5 x 9.5 cm in size, and on cross section, it was white and clearly demarcated from the surrounding tissue. Microscopic observation of hematoxylin-eosin-stained specimens did not show any glandular or trabecular formation. Histologically, there was diffuse proliferation of atypical spindle cells that had hyperchromatic, short, spindle-shaped nuclei, and pale cytoplasm with poor intercellular adhesion. The nontumorous tissue was almost normal with no sign of cirrhosis. Immunohistochemical examination showed that the spindle cells were positive for vimentin and cytokeratins (AE1/AE3, CAM 5.2), but negative for all other markers. The final diagnosis was a sarcomatoid carcinoma, the origin of which was not able to be confirmed immunohistochemically. This case of a primary hepatic tumor composed of malignant cells with sarcomatous features is described, and the immunohistochemical findings are discussed.