PSEUDOMYXOMA PERITONEI - HISTOLOGIC PREDICTORS OF PATIENT SURVIVAL

Pseudomyxoma peritonei is uncommon and the histopathologic predictors of patient survival with this disease have not been investigated exten sively. The clinicopathologic features of 35 patients with pseudomyxom atous peritoneal implants (implants that produced extracellular mucin) were compared with a control group of 90 consecutive patients with pe ritoneal implants without extracellular mucin. The histologic patterns of these nonpseudomyxomatous implants were as follows: glandular, 43% ; serous, 21%; signet ring, 20%; solid, 13%; and clear cell, 2%. The p seudomyxomatous implants were more likely to have originated from a mu cinous epithelial tumor of the appendix (31% vs 1%). Other primary sit es produced pseudomyxomatous and nonpseudomyxomatous implants with sim ilar frequency: colon (26% vs 30%), ovary (23% vs 16%), stomach (11% v s 10%), small intestine (3% vs 1%), urinary bladder (3% vs 1%), endome trium (0% vs 10%), prostate gland (0% vs 6%), and unknown (3% vs 15%). Three-year follow-up was available for 29 of 35 and 71 of 90 patients with and without extracellular mucin in their implants, respectively. The patients with pseudomyxomatous implants survived longer (24% vs 4 % survival at 3 years). Three-year follow-up was available for 90 of 1 10 and 10 of 15 patients with and without invasion in the primary tumo r of its peritoneal implants, respectively. The patients without invas ive tumors survived longer (80% vs 4% survival at 3 years). Invasion i n the primary tumor or its implants, present in 21 of 35 pseudomyxomat ous implants, eliminated any improved survival associated with the pre sence of extracellular mucin. Prolonged survival in pseudomyxoma perit onei was associated with the histologic findings of noninvasive implan ts arising from mucinous epithelial tumors of low malignant potential histology. In our study, such tumors originated in the appendix (eight cases [23%]) and ovary (five cases [14%]) among the total number of 3 5 patients.