Undifferentiated carcinoma of the liver: a case report with immunohistochemical analysis.

Background: Undifferentiated carcinoma (UC) of the liver is extremely rare, and its clinicopathological characteristics have not been fully elucidated. Case presentation: The present study reports the case of a 56-year-old male with UC of the liver. At 16 days post-admission, the patient suddenly succumbed due to intra-abdominal bleeding resulting from a ruptured liver. Macroscopic examination revealed that the hepatic parenchyma was almost completely replaced by innumerable minute nodules. Microscopically, the tumor demonstrated a diffuse proliferation of anaplastic cells that were positive for epithelial membrane antigen and neuron-specific enolase, suggesting neuroendocrine differentiation. Grimelius and Fontana-Masson staining were negative. Neuroendocrine markers were also negative, including chromogranin A, synaptophysin, and S-100 protein. Cytokeratin markers and mesenchymal markers were all negative. Tumor markers, such as α-fetoprotein and carcinoembryonic antigen, were also negative. Conclusions: Although larger studies involving more patients are required to establish a therapeutic strategy, appropriate chemotherapy following an early diagnosis may be important to UC of the liver because the tumor behaves in an aggressive way. [ABSTRACT FROM AUTHOR]