Prognostic Significance of Histomorphologic Parameters in Diffuse Malignant Peritoneal Mesothelioma

Abstract

Context. —Diffuse malignant peritoneal mesothelioma is currently regarded as a rare and lethal primary tumor arising from the peritoneal membrane. In the past, treatment plans with variable combinations of surgery and systemic chemotherapy were associated with a median survival of approximately 1 year. Standardized treatments using cytoreductive surgery and perioperative intraperitoneal chemotherapy have extended this survival. Objective. —To critically analyze the prognostic significance of histomorphologic parameters as a determinant of survival. Design. —Sixty-two consecutive patients with diffuse malignant peritoneal mesothelioma in whom data were prospectively accumulated were retrospectively analyzed by 14 different histomorphologic parameters. The influences of these pathologic characteristics on survival were critically statistically evaluated. Results. —In a univariate analysis, histologic type, nuclear/nucleolar size, stroma, depth of invasion into the bowel, atypical mitoses, mitotic index, necrosis, lymph node involvement, and chromatin patterns were found to be significant. In the multivariate analysis, histologic type and nuclear/nucleolar size remained as determinant histomorphologic characteristics. Use of biphasic/sarcomatoid histologic type as a poor prognostic characteristic was limited in that only 8% of patients showed this histology. Conclusions. —Histomorphologic parameters carry prognostic significance in predicting the survival of patients with diffuse malignant peritoneal mesothelioma when treated in a standardized fashion using cytoreductive surgery and perioperative intraperitoneal chemotherapy. Nuclear/nucleolar size was found to be a reliable histomorphologic assessment available to assess prognosis in these patients.