Morphological and clinical predictive factors in appendiceal mucinous neoplasms: A retrospective analysis of 49 cases

Appendiceal mucinous neoplasms (AMNs) represent an infrequent type of appendiceal tumour, characterised by their potential for aggressive biological behaviour and the possibility of developing peritoneal carcinomatosis. There is still uncertainty about which variables can predict the clinical evolution and recurrence risk of this disease. The primary objective of this study is to reevaluate cases of AMN diagnosed at our institution to identify morphological and clinical factors that may serve as predictors of recurrence. A retrospective study of 49 patients diagnosed with AMN at tertiary hospital from 2011 to 2023 was carried out. Histological parameters, such as architectural pattern, mitotic index, and loss of polarity, along with pre- and post-operative clinical data were collected. Variables significantly associated with the first recurrence were surgical reintervention (p=0.002), death due to AMN (p=0.008), carcinomatosis at diagnosis (p=0.003), adjuvant therapy (p=0.01), TNM stage (p=0.01), morphological pattern (p=0.02), and loss of nuclear polarity (p=0.02). Survival analysis revealed that an undulating pattern (p=0.04) and the presence of micropapillary structures (p=0.01) were associated with an increased risk of recurrence. In contrast, the risk of recurrence decreased with increasing age (p=0.02) and focal loss of nuclear polarity. The risk was higher in cases classified as HAMN (p=0.008). The results indicate that age and focal loss of nuclear polarity are inversely correlated with recurrence risk, while an undulating pattern and the presence of micropapillary structures are directly correlated with time to first recurrence. These findings contribute to improved risk stratification and the optimization of therapeutic strategies for patients with AMN.