Appendiceal Mucinous Neoplasms: From Clinic to Pathology and Prognosis

Appendiceal mucinous neoplasms have been classified differently over time causing confusion when comparing results between working groups in this field and establishing a prognosis of the disease. A historical perspective of the different classification systems of these tumors is essential for the understanding of the evolution of concepts and histopathological definitions that have led up to the present moment. We carried out a systematic review of the pathological classifications of appendiceal mucinous tumors and how they have included the new criteria resulting from clinical and pathological research. The latest classifications by PSOGI and AJCC 8th edition Cancer Staging have made a great effort to incorporate the new pathological descriptions and develop prognostic groups. The introduction of these new classification systems has posed the challenge of verifying how they adapt to our casuistry and which one defines best the prognosis of our patients. We reclassified our series of patients treated for mucinous appendiceal tumors with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy following the PSOGI and the AJCC 8th edition criteria and concluded that both classifications correspond well with the OS and DFS of these patients, with some advantage relative to the PSOGI classification due to a better histopathological description of the different groups.

Comparing Survival Outcomes and Impact of EPIC in Patients Undergoing CRS/HIPEC for Mucinous Appendiceal Neoplasm

BACKGROUND/AIM

This study sought to investigate the difference in survival outcomes in patients with complete cytoreduction (CC)-0 or CC-1 mucinous appendiceal cancer undergoing cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC). It also investigated what effect early postoperative intraperitoneal chemotherapy (EPIC) may have on survival based on CC score and histology.

PATIENTS AND METHODS

This was a retrospective single centre study of patients that underwent CRS/HIPEC +/- EPIC for mucinous appendiceal neoplasms from June 2003 to February 2022.

RESULTS

A total of 545 patients were identified. Although there was a survival difference between CC-0 and CC-1 on univariate analyses, this was not statistically significant on multivariate analysis. Histology, peritoneal cancer index, and EPIC status were demonstrated to be independent factors that affected overall survival (OS) on multivariate analysis. Patients with CC-1 that received EPIC had significantly improved OS (mean OS 14 years) when compared to patients that did not receive EPIC (mean OS 6 years). In CC-1, OS was significantly improved in patients that received EPIC in both low-grade (p<0.001) and high-grade (p=0.012) disease. OS for patients that received EPIC at 1, 5, and 10 years was 95%, 80%, and 59%, respectively. OS for patients that did not receive EPIC at 1, 5, and 10 years was 84%, 49%, and 30%, respectively.

CONCLUSION

There was no difference in OS between CC-0 and CC-1. The implementation of EPIC in patients with CC-1 significantly improved OS in both low-grade and high-grade disease and thus we recommend its addition in CC-1 disease to achieve optimal survival outcome.

Utility of computed tomography and 18 F-fluorodeoxyglucose with positron emission tomography/computed tomography for distinguishing appendiceal mucocele caused by mucinous adenocarcinoma from other pathologies

AIM

Differentiating appendiceal mucocele with mucinous adenocarcinoma from other pathologies before surgery is difficult. The objective of this study was to evaluate the utility of CT and ¹⁸ F-fluorodeoxyglucose (FDG) with positron emission tomography (PET)/CT for differentiating mucinous adenocarcinoma of appendiceal mucocele from other pathologies.

METHOD

The study included 25 patients who underwent surgery for clinically diagnosed appendiceal mucoceles detected on CT at the University of Tokyo Hospital. Among these patients, 19 underwent FDG-PET/CT preoperatively. We compared features of the CT imaging findings and maximum standard uptake values (SUV_max ) detected by FDG-PET/CT between mucocele with mucinous adenocarcinoma and other pathologies.

RESULTS

A total of 13 men (52%) and 12 women (48%) were included in this study, with a median age of 65 years (range 34-83). There were six patients (24%) with pathologically confirmed mucinous adenocarcinoma, 15 patients (60%) with appendiceal mucinous neoplasm and four patients (16%) with simple mucocele caused by chronic inflammation. On the CT findings, wall irregularity was the only significant feature for the two groups in this study (83.3% vs 0.0%, P < 0.01). There was a significant difference in the SUV_max levels on PET/CT between the two groups (100.0% vs 20.0%, P < 0.01).

CONCLUSION

Distinguishing between mucocele with mucinous adenocarcinoma and other pathologies using imaging modalities is challenging. Our results suggest that wall irregularity on CT and elevated SUV_max on PET/CT are useful factors that can be employed for such discrimination.