Krukenberg tumor with yolk sac tumor differentiation

An unusual case of bilateral Krukenberg tumor with foci of yolk sac tumor (YST) differentiation occurring in a 50-year-old patient is reported. The primary tumor was in the gastric antrum, and it showed morphology of poorly differentiated adenocarcinoma with diffuse and solid growth pattern. A component of typical YST was not found in the gastric primary and lymph node metastases, although some cells in these locations were positive for alpha-fetoprotein. In the ovarian metastases, YST element showed microcystic/reticular and solid patterns, whereas the adenocarcinoma component was of diffuse type with signet ring cells and with some undifferentiated areas. The case represents further example of the somatic cell-derived tumor with focal germ cell-type differentiation and the first report of YST differentiation in Krukenberg tumor.