Primary fibrosarcoma of the liver. Immunohistochemical and electron microscopic studies.

An autopsy case of primary fibrosarcoma occurring in the liver of a 75-year-old female is presented. The tumor, arising from the lateral upper portion of the right lobe, measured 14 cm in greatest dimension. Light microscopy of the tumor revealed homogeneous, spindle-shaped cells with abundant collagen fibers showing a classic herring-bone pattern. Immunoreactive vimentin was found in the tumor cells. Electron microscopically, the tumor cells were rich in rough endoplasmic reticulum without a basement membrane, and were surrounded by large amounts of collagen fibers. The fibroblastic character of the tumor cells was suggested by light and electron microscopy. This may be the first reported case of primary hepatic fibrosarcoma examined by immunohistochemistry and electron microscopy.