Krukenberg tumors are usually bilateral, large multinodular tumors of metastatic origin involving the ovaries. Microscopically, they are usually composed of signet ring cells diffusely infiltrating the ovarian stroma. The signet ring appearance is created by the presence of copious amounts of neutral and acidic mucins. The usual primary sites include stomach, colon, appendix, and breast. This specimen shows one of the ovaries with a large multinodular tumor in a 80 y/o female with adenocarcinoma of the appendix. Courtesy of: Dr. Katharina Glatz-Krieger, Institute for Pathology, Basel, Switzerland.