When 'Mucocele' Isn't Just a Mucocele: Diagnostic Pathways and Surgical Management of Appendiceal Mucinous Lesions in a 10-Year Cohort.

Background and Objectives: The term "appendiceal mucocele" is widely used in clinical practice, yet it remains diagnostically incomplete because it represents a preoperative clinical and imaging label rather than a definitive diagnosis. We examined the diagnostic and therapeutic pathway of patients managed under this working label over a 10-year period and assessed how final histopathology influenced subsequent management. Materials and Methods: We performed a retrospective single-center cohort study including patients with appendiceal mucinous lesions managed between January 2016 and December 2025. Eligible cases were identified from the institutional histopathology registry and classified on final histopathology as non-neoplastic mucoceles or neoplastic mucinous lesions, including low-grade and high-grade appendiceal mucinous neoplasms. Data were extracted on CT use, surgical strategy, margin status, extra-appendiceal/serosal mucin, chemotherapy, recurrence, and follow-up. Results: Eighteen patients met the eligibility criteria. Final histopathology showed two distinct endpoints: non-neoplastic mucoceles and neoplastic mucinous lesions. CT was the dominant preoperative investigation and most often supported the working impression of mucocele or suspected mucinous appendiceal lesion, although some neoplastic cases entered the pathway as presumed appendicitis or perforation. Appendectomy was the dominant index procedure, whereas primary right hemicolectomy was uncommon. Completion right hemicolectomy was performed only in the neoplastic subgroup, and management decisions were driven by a limited number of actionable histopathologic features, particularly margin status and extra-appendiceal/serosal mucin. Conclusions: This study highlights a real-world diagnostic and therapeutic pathway in which the term "mucocele" represents a preoperative label rather than a definitive diagnosis. Histopathology appeared to represent the key step in this pathway, rather than the preoperative imaging impression. Given the small sample size, these findings should be interpreted as descriptive and hypothesis-generating. In practical terms, suspected appendiceal mucocele should be approached through a standardized pathway involving safe index resection, structured pathology reporting using modern terminology, and risk-adapted escalation and follow-up when higher-risk features are present.