Appendiceal Incidentalomas: Prevalence, Radiographic Characteristics, Management, and Outcomes.

BACKGROUND: Radiographically detected incidental appendiceal abnormalities, in this report termed "appendiceal incidentalomas" (AIs), are an ill-defined entity with an unknown prevalence of neoplasm. This study aimed to describe the prevalence, radiographic characteristics, and outcomes of patients with a diagnosis of AI. METHODS: The study reviewed the electronic health records for patients at a single institution undergoing abdominopelvic computed tomography and magnetic resonance imaging (MRI) from 2000 to 2020 for non-appendix-related complaints with mention of appendix abnormality in the radiology report. The suggested diagnosis at the index imaging was recorded. Outcomes were compared between the operative and non-operative patients. RESULTS: Of 5197 records, 484 were identified as reports of AIs (9 % of screened patients). Neoplasms were suggested radiographically in 16 % (n = 79) of the records, 59 % (47/79) of which were resected. Pathologically, 32 of the abnormalities were confirmed as neoplasms, yielding a diagnostic accuracy of 68 %. Compared with the non-operative patients, the operative patients had AIs with a larger mean diameter (22.7 ± 13.0 vs. 17.8 ±7.7 mm; p = 0.04), a higher colonoscopy rate (51 % vs. 22 %; p = 0.01), and diagnosis at a younger age (55.8 ± 15.6 vs. 67.2 ± 16.0 years; p = 0.003). The postoperative complications were minor (Clavien-Dindo grade 1 or 2) in 26 % and major (grades 3-5) in 4 % of the cases. During a median follow-up period of 28.3 months, 94 % of the patients were alive without disease, and 6 % died of other causes. The 32 non-operative suggested neoplastic AIs had a median follow-up period of 20.9 months. At this writing, 59 % of the operative patients are alive with a stable abnormal appendix, 13 % had no appendix abnormality at last follow-up visit, and 28 % have died of other causes. CONCLUSION: Neoplastic AIs are an uncommon finding and radiographically diagnosed with relatively high accuracy. Larger appendiceal diameter and younger age predict operative intervention. Although surgery is associated with favorable outcomes and minimal risk of postoperative complications, observation of suspected neoplastic AIs may be a safe alternative for select patients undergoing follow-up longitudinal imaging.

Preoperative Radiographic Assessment Predicts Incomplete Cytoreduction in Patients with Low Grade Mucinous Adenocarcinoma of the Appendix.

BACKGROUND: Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) for patients with low-grade mucinous adenocarcinoma (LGMA) is most effective when complete cytoreduction is achieved. We externally validated two radiographic scoring systems to predict resectability and assessed radiographic response to systemic chemotherapy (SCT). METHODS: Patients with LGMA who received preoperative SCT followed by CRS/HIPEC from 2013 to 2016 were identified. CT scans were graded by six physicians using the simplified radiologic score (SRS) and simplified preoperative assessment of appendiceal tumor (SPAAT) systems. Positive and negative predictive values (PPV, NPV) were calculated by comparing to completeness of cytoreduction. Inter-rater agreement was assessed using the intraclass correlation coefficient (ICC). RESULTS: Twenty-four patients had preoperative SCT followed by CRS/HIPEC. Thirteen patients underwent incomplete CRS and 11 patients complete CRS. Scoring of the preoperative CT had a PPV of complete cytoreduction of 75% and 66.7% for SRS and SPAAT, respectively. NPV was 83.4% and 88.9% for SRS and SPAAT, respectively. ICC for the preoperative SRS and SPAAT score was 0.826 (95% confidence interval [CI]: 0.720-0.910] and 0.788 [0.667-0.888). Comparison of CT scans before and after SCT recorded an increase in calculated scores in 45.8% (SRS) and 50% (SPAAT) of patients. CONCLUSIONS: External validation of two radiographic scoring systems to predict complete cytoreduction showed that inter-rater agreement for both systems was good. Both scoring systems predicted incomplete cytoreduction. Applying a systematic approach to preoperative imaging review is recommended to improve treatment selection by minimizing morbidity associated with incomplete CRS and help to set patient expectations.

Computed Tomography Follow-Up Assessment of Patients with Low-Grade Appendiceal Mucinous Neoplasms: Evaluation of Risk for Pseudomyxoma Peritonei.

BACKGROUND: Low-grade appendiceal mucinous neoplasms are rare. Both classification and management vary. This study aimed to follow up on patients with a diagnosis of LAMN after primary surgery with computer tomography (CT) scans to examine the risk for the development of pseudomyxoma peritonei (PMP). METHODS: This population-based prospective study investigated patients who underwent appendectomy between 2007 and 2013 and had histology results demonstrating the presence of LAMN. The patients were followed up with a CT scan every 6 months for 2 years, until December 2015. RESULTS: The study investigated 41 patients (20 females) with a median age of 65 years (range 20-87 years). The entire appendix was processed and examined, with results showing that 12 were perforated, and 3 had a positive margin. Extra-appendiceal mucin on the surface of the appendix was found in ten cases, and in two cases, extra-mucinous epithelial cells were detected. During a median follow-up period of 5.1 years (range 2-8.6 years), none of the patients experienced the development of PMP. CONCLUSIONS: These data suggest that for patients with LAMN confined to the appendix, involvement of the appendectomy margin or perforation with mucin locally, even with epithelial cells, did not predict the development of PMP, and a conservative approach seems justified. No reoperation was needed, and regular follow-up evaluation with CT scans was sufficient.

External Validation of the Simplified Preoperative Assessment for Low-Grade Mucinous Adenocarcinoma of the Appendix.

BACKGROUND: MD Anderson Cancer Center developed a computed tomography (CT)-based preoperative assessment tool simplified preoperative assessment for appendix tumor (SPAAT) for predicting incomplete cytoreduction (IC) in low-grade mucinous adenocarcinoma (LGMA) of the appendix, based on preoperative CT scans. This study independently evaluates the tool's performance. METHODS: Seventy-six preoperative CT scans of LGMA patients were evaluated by two surgeons unfamiliar with the patients' medical history. Scores were assigned based on SPAAT criteria, with a SPAAT ≥3 predictive of IC. Binary regression analyses and area under the receiver operating characteristic (AUROC) curve analyses were performed. Patients with splenic resection were excluded due to the structure of the SPAAT assessment tool. RESULTS: Seventy-six LGMA patients underwent attempted cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). Of 68 patients, 58 had complete cytoreduction and 10 had IC; 8 patients were ineligible due to prior splenectomy. The mean SPAAT score was 0.8, with six patients having SPAAT scores ≥3. SPAAT scores ≥3 were predictive of IC, with a hazard ratio (HR) of 19 (95% confidence interval 2.8-124.1) (p = 0.002). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value were 40, 97, 50, and 90%, respectively. A SPAAT score ≥3 was not associated with worse survival prognosis. Median follow-up was 2.4 years and AUROC curve was 71%. SPAAT components with respective HR and p-values were foreshortening of the bowel mesentery (29.5; p = 0.004), and scalloping of the pancreas (9; p = 0.008), spleen (4.3; p = 0.04), portal vein (3.1; p = 0.4), and liver (2.1; p = 0.3). CONCLUSION: A SPAAT score ≥3 predicted IC based on a binary regression model. The clinical value of this score is controversial due to low sensitivity and PPV.

A Simplified Preoperative Assessment Predicts Complete Cytoreduction and Outcomes in Patients with Low-Grade Mucinous Adenocarcinoma of the Appendix.

BACKGROUND: Complete cytoreduction with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) has been shown to improve survival in patients with low-grade mucinous adenocarcinoma (LGMA). However, incomplete cytoreduction exposes patients to significant morbidity without a similar survival benefit. Preoperative assessment of the ability to achieve CRS is therefore a critical step in selecting patients for CRS/HIPEC. OBJECTIVE: The aim of this study was to develop and validate a preoperative scoring system to accurately predict the ability to achieve complete cytoreduction in patients with LGMA of the appendix. METHODS: A simplified preoperative assessment for appendix tumor (SPAAT) score was developed based on computed tomography scan findings thought to predict incomplete cytoreduction. We applied the SPAAT score to patients with LGMA to determine the ability of the score to predict complete cytoreduction. This scoring system was then applied to a separate cohort of patients from a different institution. Sensitivity and specificity were determined for the SPAAT score. Survival was calculated and correlated with the SPAAT score and the completeness of cytoreduction score. RESULTS: A SPAAT score of <3 is a significant predictor of complete cytoreduction in the derivation cohort. In the validation cohort, 40 of 42 patients with a SPAAT score <3 achieved a complete cytoreduction, for a positive predictive value of 95.2 % and a negative predictive value of 100 %. Additionally, the SPAAT score was a significant predictor of disease-free survival. CONCLUSIONS: The SPAAT score is a useful tool in the preoperative assessment of patients with LGMA who are under consideration for cytoreductive surgery. Prospective analysis of this scoring system is warranted to appropriately select patients who will benefit from CRS/HIPEC.