Ovarian Cancer. Peritoneal Lesions, Metastases vs Multicentricity.

Low-grade serous carcinoma in the vermiform appendix. In some cases it is obvious that peritoneal lesions cannot be metastases. In very early lesions involving the GI tract, tumors can be seen deep into the muscularis propria and submucosa, without involvement of the serosa.

Another important issue regarding the involvement of ovarian serous tumors in the GI tract is that the rectosigmoid is the most frequent site of "metastases", and the vermiform appendix, the smallest part of the intestine, it is more frequently involved than the small bowel. Both, the rectosigmoid and the appendix, are frequently involved by a precursor of ovarian epithelial tumors, endometriosis.

A more extensive discussion, including the review of 289 serous tumors involving the peritoneum, can be found in the Fere Ex Nihilo book, Chapter 7, Peritoneal Serous Tumors: Metastases vs Multicentricity.