Clinicopathological Features and Management of Appendiceal Mucoceles: A Systematic Review.

Appendiceal mucoceles (AMs) are rare mucin-containing neoplasms with malignant potential. Lack of evidence-based data exists defining clinicopathological features for management. MEDLINE search between 1995 and 2015 was performed using search criteria "Appendix mucocele." Systematic review of patient-, pathologic-, and treatment-related characteristics was performed and data analyzed. Among 276 cases of non-perforated AMs, 163 (59%) patients were female, with variable and nonspecific presentation. Patients were treated with appendectomy (52.1%), right hemicolectomy (17.6%), partial cecectomy (17.2%), and ileocecetomy (13.1%). Pathologic evaluation revealed the following: cystadenoma/low-grade appendiceal mucinous neoplasm (54%), unspecified/benign (25%), retention cyst (14.1%), cystadenocarcinoma (4.2%), and mucosal hyperplasia (2.9%). All 11 (4.2%) patients with cystadenocarcinoma were female (P = 0.004), odds ratio for malignancy 1.07 times higher for women. Synchronous colonic malignancy was reported in three patients (27%) with cystadenocarcinoma (P = 0.007), odds ratio of 12.1. AMs have low risk for malignancy. Treatment should begin with appendectomy-only and subsequently guided by pathologic diagnosis.

Appendix-derived Pseudomyxoma Peritonei (PMP): Molecular Profiling Toward Treatment of a Rare Malignancy.

OBJECTIVES: Pseudomyxoma peritonei (PMP) is a rare malignancy originating from the appendix, characterized by disseminated mucinous tumor implants on peritoneal surfaces. We examined the role of multiplatform molecular profiling to study biomarker-guided treatment strategies for this rare malignancy. METHODS: A total of 54 patients with appendix-derived PMP were included in the study. Tests included one or more of the following: gene sequencing (Sanger or next generation sequencing), protein expression (immunohistochemistry), and gene amplification (C/fluorescent in situ hybridization). RESULTS: Targeted sequencing of 47 genes detected variants in KRAS (81%), GNAS (74%), SMAD4 (16%), and ATM (16%). Mutations were found at low frequencies (n=1 to 2) in APC, BRAF, PIK3CA, MLH1, and TP53. GNAS and KRAS co-occurrence was found in 87%. Protein overexpression was found in epidermal growth factor receptor (83%), cyclooxygenase-2 (73%), cMET (63%), cKIT (58%), and platelet-derived growth factor receptor alpha (58%). Immune checkpoint expression was found in 36% (programmed cell death protein 1) and 18% (programmed death-ligand 1). Surrogate markers of cell proliferation were found at low rates (TLE3 23%, TOP2A 22%), consistent with the slow-growing biology of PMP. Phosophatase and tensin homolog was intact (wild type [100%]) and positive (immunohistochemistry [80%]). Patients exhibited stable microsatellite status and mismatch repair proficiency (93%). Importantly, multidrug resistance protein expression was elevated (100% BCRP, 94% MRP1, 88% PGP). Markers for gemcitabine (RRM1), fluorouracil (TS), oxaliplatin (ERCC1), and irinotecan (TOPO1) chemosensitivities were detected at favorable rates: 93%, 87%, 77% and 65%, respectively. CONCLUSIONS: Molecular profiling by multiple platforms identified potential therapies for the nontargetable KRAS-mutated population. The role of cMET-targeted therapeutics and immune checkpoint inhibitors merits further investigation. Biomarker-guided selection of cytotoxic chemotherapies may facilitate efficacy to systemic treatment.

Recurrent Gastrointestinal Stromal Tumors in the Imatinib Mesylate Era: Treatment Strategies for an Incurable Disease.

INTRODUCTION: Recurrence of gastrointestinal stromal tumors (GISTs) after surgical resection and imatinib mesylate (IM) adjuvant therapy poses a significant treatment challenge. We present the case of a patient who underwent surgical resection after recurrence and review the current literature regarding treatment. CASE PRESENTATION: A 58-year-old man with a large intra-abdominal jejunal GIST was treated with complete surgical resection followed by IM. The patient experienced disease recurrence 3.5 years later and underwent IM dose escalation and reresection. CONCLUSION: Current strategies to treat recurrent GIST include dose escalation, modifying adjuvant tyrosine kinase inhibitor therapy, and surgery. High-level evidence will be required to better define the combinatory roles of tyrosine kinase inhibitor therapy, guided by molecular profiling, and surgery in the management of recurrent GIST.

Incidentally discovered low-grade appendiceal mucinous neoplasm: a precursor to pseudomyxoma peritonei.

Appendiceal mucoceles (AMs) infrequently arise from an underlying malignancy. Treatment has progressed toward a less aggressive approach over time; they can be managed by appendectomy-only unless pathology reveals malignancy. The ultimate goal of management is to prevent AM rupture, avoiding the syndrome of pseudomyxoma peritonei.