Gelatinous ascites: A cytohistologic study of pseudomyxoma peritonei in 67patients

Background: Pseudomyxoma peritonei (PMP) is a rare condition characterized by gelatinous ascites. Although the histologic attributes of PMP have been well studied, the cytologic features remain ill defined. Methods: We review ed the peritoneal washings (PW) in 67 patients with PMP to identify cytomor phologic features useful in classifying cases as either disseminated perito neal adenomucinosis (DPAM) or peritoneal mucinous carcinomatosis (PMCA). Hi stologic specimens were correlated with the cytologic diagnoses. Correlatio n between cytologic diagnosis and patient outcome was investigated. Results : Neoplastic epithelial cells were identified in 63 of 67 PW (94%). Concord ance with the histologic diagnosis was obtained in 61 of 63 cases. Of these 36.5% were cytologically classified as DPAM with primary appendiceal neopl asms in :19 cases. Thirty-four of 63 cases (53.9%) were cytologically diagn osed as PMCA based on PW cytology. Most were of appendiceal or colonic orig in. Four cases displayed cytologic features of both DPAM and PMCA. Two disc ordant cases each with a cytologic diagnosis of PMCA had an appendiceal ade noma. Acellular mucin alone was identified in the PW in four cases. analysi s of follow-up data revealed that cases diagnosed as DPAM had a better prog nosis than those diagnosed as PMCA. Conclusions. Cytomorphologic features o f epithelial cells in PW material can accurately categorize cases of PMP as either DPAM or PMCA. Furthermore, this categorization appears to have impo rtant prognostic implications.