PSEUDOMYXOMA PERITONEI - A CLINICOPATHOLOGICAL STUDY OF 19 CASES WITHEMPHASIS ON SITE OF ORIGIN AND NATURE OF ASSOCIATED OVARIAN-TUMORS

Nineteen patients (10 men, 9 women) with pseudomyxoma peritonei were s tudied to determine the site of origin of the disease and the nature o f associated ovarian tumors. A primary appendiceal mucinous neoplasm w as found in 16 of the 17 patients with an evaluable appendix. One woma n's appendix had intramural and serosal mucinous deposits without neop lastic epithelial cells. The appendiceal tumors were classified as muc in-producing adenoma (''mucinous cystadenoma'') in 13 patients (seven women, six men), intramucosal adenocarcinoma associated with mucin-pro ducing adenoma in one man, and invasive adenocarcinoma associated with mucin-producing adenoma in one man and one woman. Five of the nine wo men had cystic mucinous ovarian neoplasms; each also had an appendicea l mucinous neoplasm (adenoma in four, invasive adenocarcinoma with ade noma in one). The ovarian neoplasms had histologic features resembling a borderline (low malignant potential) mucinous tumor in four and a m ucinous cystadenoma in one; all five ovarian tumors also had features of pseudomyxoma ovarii. Mucinous implants were also on the ovarian sur face of the contralateral ovary in four of the five women with ovarian tumors and in the other four women without ovarian tumors. The intrap eritoneal mucus deposits contained neoplastic mucinous epithelial cell s in 16 patients (eight men, eight women) and were acellular in three (two women, one man). Of 17 patients with more than 6 months of follow -up, 12 (seven women, five men) were alive after postoperative interva ls of 7 to 147 months, including three with known residual disease. Fi ve (three men, two women) died of disease 16 to 60 months after initia l operation, including two patients with appendiceal carcinoma. Acellu lar intraperitoneal mucus appeared to be a favorable prognostic featur e. We conclude that (a) the appendix is the primary site of origin of pseudomyxoma in the vast majority of cases in both men and women, and (b) the associated mucinous ovarian tumors are most likely secondary n eoplasms resulting from incorporation of implanted mucus and neoplasti c mucinous epithelial cells of the pseudomyxoma peritonei.