Histopathologic analysis in 46 patients with pseudomyxoma peritonei syndrome: Failure versus success with a second-look operation

Pseudomyxoma peritonei syndrome is a disease characterized by mucinous asci tes and mucinous tumor disseminated on peritoneal surfaces; the disease alm ost always originates from a perforated appendiceal epithelial tumor. Histo pathologic assessment of aggressive versus noninvasive character of the muc inous tumor has been shown to have an impact on survival in patients treate d with cytoreductive surgery and intraperitoneal chemotherapy. Out of a dat abase of 312 patients having a complete cytoreduction for pseudomyxoma peri tonei syndrome, 46 patients (24 male and 22 female) had at least one second -look surgery, Before this review, all 46 of these patients were clinically uniformly categorized with a diagnosis of pseudomyxoma peritonei, Using th e criteria described by Ronnett and colleagues, all specimens from the mult iple surgical procedures performed on these patients were reviewed and recl assified as disseminated peritoneal adenomucinosis (adenomucinosis), adenom ucinosis/mucinous adenocarcinoma (hybrid), or mucinous adenocarcinoma. The review was performed in a blinded fashion by a single pathologist (KY), To facilitate a critical evaluation of these histopathologic assessments, the patients were separated into two groups: (1) 19 patients who had a second-l ook surgery that was unsuccessful in that they went on to die of their dise ase or in that they currently have disease progression and a limited surviv al and (2) 27 patients who had a successful second look and currently conti nue disease free with a minimum 3-year follow-up period, As a result of thi s review, 11 of 19 patients with an unsuccessful second look and originally designated pseudomyxoma peritonei were reclassified as hybrid-type maligna ncy (four patients) or mucinous adenocarcinoma (seven patients), Only two p atients were reclassified in the successful second-look group (P = .0005), Transitions from a less aggressive to a more invasive histology from one cy toreduction to the next occurred on 13 occasions in patients whose second-l ook surgery failed and in one patient with a successful second-look surgery (P < .0001), Seven patients retained a histologic classification of dissem inated peritoneal adenomucinosis but went on to die of an aggressive diseas e process. Clinical assessments suggested that failure of second-look surge ry for pseudomyxoma peritonei was associated with a biologically more aggre ssive disease. Unsuccessful second-look surgery for patients with a clinica l diagnosis of pseudomyxoma peritonei tumor was often related to an inaccur ate initial histologic classification of appendiceal mucinous tumor. Also, a transition from less to more aggressive histology was frequently seen in patients dying of this disease. Assessment of tumor histology can predict t he outcome if a uniform surgical treatment is used in patients with periton eal dissemination of mucinous epithelial tumors of the appendix.