Localized fibrous tumor (localized fibrous mesothelioma) of the liver.

A case of localized fibrous tumor (LFT) (localized fibrous mesothelioma) of the liver in an 83-year-old woman is presented. The tumor was 15 x 9 x 8 cm and was confined to the left lateral segment of the liver. Occasional mitotic figures (MF) (2 to 3 per 50 high-power fields [HPF]) were present. Strong, diffuse vimentin positivity was demonstrated by immunohistochemistry. Immunoreactivity for cytokeratins (AE1-3), epithelial membrane antigen (EMA), desmin, and desmosomal proteins (desmoplakin I + II) was absent. Electron microscopic examination showed a mesenchymal appearance of the majority of neoplastic cells, with a few ultrastructural features suggestive of mesothelial differentiation. These findings supported a submesothelial origin of the tumor. After a partial hepatectomy with total gross and microscopic removal of the tumor, the patient was alive without recurrence at 2 years, 5 months later. A review of the English literature showed six additional cases that are probably similar. Currently, all tumors have been clinically benign, although follow-up information has been limited.