Krukenberg tumors of the ovary. Ultrastructural, histochemical and immunohistochemical studies of 15 cases.

The ultrastructural, histochemical, and immunohistochemical characteristics of 12 classical signet ring cell Krukenberg tumors (CKT) and three tubular Krukenberg tumors (TKT) were evaluated and related to their possible influence on the ovarian stroma. In CKT, single signet ring cells predominated over lumen-forming cells and contained ultrastructural and histochemical characteristics similar to goblet cells in colonic and ovarian mucinous adenocarcinomas. In TKT, lumen-forming nonsecretory and secretory signet ring cells were prominent. Rare argentaffin cells were found in TKT but not in CKT. Cells in both CKT and TKT produced neutral and sialomucins. The stroma contained extracellular mucin, hypertrophied stromal fibroblasts and myofibroblasts, and in two cases stromal lutein cells with steroidogenic type ultrastructure. It appears that Krukenberg tumors are made up exclusively of intestinal type cells. Based on cell differentiation, TKT is better differentiated than CKT. Hypertrophy and hyperplasia of ovarian stromal cells may occur in response to malignant growth and/or the extracellular mucinous products of malignant cells and may play a role in the control of tumor invasiveness. None of the 15 cases were immunohistochemically positive for chorionic gonadotropin, placental lactogen, or luteinizing hormone. These hormones are suspected to be related to stromal luteinization in KT.