From krukenberg to today: the ever present problems posed by metastatic tumors in the ovary: part I. Historical perspective, general principles, mucinous tumors including the krukenberg tumor.

This review considers historical aspects of metastatic tumors to the ovary, general principles that aid in their evaluation, and metastatic mucinous tumors, including the Krukenberg tumor. The historical timeline on the Krukenberg tumor dates back to the legendary Sir James Paget and the story is followed through the well-known, albeit flawed, contribution of Friedrich Krukenberg and others who have contributed important papers over the years, including the overlooked contribution of the French investigator Gauthier-Villars. Knowledge of metastatic colorectal carcinoma is traced back to the famed British surgeon Sir John Bland-Sutton and followed through to more recent contributions, including the important one of Lash and Hart. Contributions on mucinous tumors conclude the historical perspective, note being made of the recent evidence suggesting that the long held contention of Dr Robert E. Scully that ovarian mucinous tumors in patients with pseudomyxoma peritonei usually originate from the appendix is correct. The section on general principles highlights the many clinical, gross, microscopic, and special techniques such as immunohistochemistry that may aid in determining that an ovarian tumor is metastatic with emphasis on the first 3 mentioned aspects. Problematic features such as a tendency for metastatic tumors to be cystic, even when the primary tumors are not, and for many metastatic tumors to mature in the ovary (so-called maturation phenomenon), are emphasized. Of the many helpful findings that resolve the problem, the characteristic features of surface implants are highlighted. The contribution on the Krukenberg tumor reviews the varied microscopy of this tumor pointing out that the well-known pattern of signet-ring cells in a cellular stroma, albeit characteristic, is often not striking and frequently overshadowed by other microscopic features. The latter include, in many cases, a rather unique microcystic pattern. The final portion of the essay reviews mucinous tumors of non-Krukenberg type, beginning with those that originate from the appendix. The appendiceal neoplasms have distinctive features in most cases being particularly well differentiated, and this is also seen in their ovarian metastases. Other mucinous tumors that commonly simulate closely metastatic neoplasms, include those from the pancreas in particular, but also diverse other sites, are then reviewed.