Pseudomyxoma peritonei

Pseudomyxoma peritonei

PMP is a rare condition typified by progressive peritoneal tumour deposits, mucinous ascites, omental cake ( 76.17 ) and ovarian involvement in females. The vast majority of cases arise as a result of perforation of a mucinous appen diceal tumour. Patients typically present with progressive and massive abdominal distension, anor exia and symptoms of bowel dysfunction. The condition is invariably fatal without intervention. Traditionally , PMP was thought to have an incidence of 1 per 1 /uni00A0 000 /uni00A0 000 per year, but it is now thought to be at least double that with recent estimates of 3.2 cases per 1 /uni00A0 000 /uni00A0 000 per year. The overall risk of developing pseudomyx oma following removal of an appendix harbouring epithelial tumour is approximately 9%, with the risk varying according to the tumour subtype and the mode of presentation, while it may be as high as 30–50% in the case of a mucinous adeno carcinoma of the appendix ( Figur e 76.18 ). PMP is classified according to the degree of cytological atypia within the peritoneal deposits ( Table 76.4 ) and its grading may di ff er from that of the causative primary appendiceal tumour. Elevated tumour mar kers (CEA, CA-125, CA-19-9) - - Figure - - -

(b) Figure 76.18 (a) Contrast-enhanced axial computed tomography (CT) image demonstrates a tubular cystic structure with calci /f_i cation adjacent to the caecum compatible with an abnormally distended appendix (arrow). (b) Six-year follow-up postcontrast axial CT image demonstrated a 19 × 10 × 17 cm complex cystic mass in the right lower quadrant (arrow) highly suspicious for a mucinous tumour of the appendix with extensive peritoneal involvement and pseudomyxoma peritonei (courtesy of Professor Helen Fenlon, Dublin, Ireland). TABLE 76.4 Classi /f_i cation of pseudomyxoma peritonei. Acellular mucin Low-grade mucinous carcinoma peritonei High-grade mucinous carcinoma peritonei High-grade mucinous carcinoma peritonei with signet ring cells Adapted from Carr NJ, Cecil TD, Mohamed F et al . A consensus for classi /f_i cation and pathologic reporting of pseudomyxoma peritonei and associated appendiceal neoplasia. The results of the Peritoneal Surface Oncology Group International (PSOGI) modi /f_i ed Delphi process. Am J Surg Pathol 2016; 40 : 14–26.

predict a more aggressive phenotype and are associated with a worse prognosis.

P T Figure 76.19 Hyperthermic intraperitoneal chemotherapy (HIPEC) delivery following cytoreductive surgery using a closed abdomen technique. The perfusion pump (P) heats and circulates chemother apy throughout the abdominal cavity via in /f_l ow and out /f_l ow tubing (T), typically for 60–90 minutes.