[Krukenberg tumor of the ovary]

Light microscopic, ultrastructural and histochemical observation of 46 cases of ovarian Krukenberg tumors are described. The clinical material is also analysed. The histologic classification of this tumor is suggested to be four types: 1. classical Krukenberg tumor (CKT), 27 cases; 2. tubular Krukenberg tumor (TKT), 9 cases; 3. sclerosing Krukenberg tumor (SKT), 5 cases; and 4. mixed Krukenberg tumor (MKT), 5 cases. In CKT, single signet ring cells predominated over lumen-forming cells and contained ultrastructural and histochemical characteristics similar to cylindral cells of colonic and ovarian mucinous adenocarcinomas. The stroma contained extracellular mucin. In TKT, the lumen was formed by non-secretory and secretory cylindral cells. Some rare argentaffin cells were observed. Steroidgenic stromal lutein cells were identified in one case by electron microscope. Cells in both CKT and TKT produced neutral and sialomucins. Hypertrophic stromal fibroblasts were extremely rich in five SKT with signet ring cells occasionally located inside. It is easy to be misdiagnosed as fibroma or sclerosing stromal tumor. Five cases of MKT showed the mixed features of the above two or three types. Krukenberg tumors are almost always made up of intestinal type cells basing on cell differentiation. The TKT is better differentiated than CKT and SKT. Hypertrophy and hyperplasia of ovarian stromal cells may occur in response to malignant growth or the extracellular mucinous products of malignant cells. They may play a role in the control of tumor invasion.