Primary yolk sac tumor of the liver. An autopsy case with ultrastructural and immunopathological studies.

An autopsy case of yolk sac tumor of the liver in a 29-year-old female was reported. The tumor was found originally in the right anterior segment of the liver on the first operation. The autopsy disclosed that the liver was almost entirely replaced by multiple, round tumor nodules. The tumor masses continuously extended to the peritoneum and to the subcutaneous tissue. There were no tumors in other organs including the ovaries, gut, stomach, lung, uterus, and kidneys, indicating that the tumor originated in the liver. Microscopically, the tumor showed typical characteristics of the yolk sac tumor. An immunohistochemical study showed that AFP was distributed fine granularly in the cytoplasm of tumor cells. Electron microscopic observation disclosed large amounts of electron-dense material being closely related to basement membrane.