Appendiceal mucinous neoplasms: Optimizing treatment strategies based on clinical, histological, and molecular features

Figure 1 Abdominal contrast-enhanced computed tomography scan (axial view). A 38-mm cystic mass was observed within the appendix. It features a non-enhanced hypodense area and surrounding curvilinear calcifications (yellow arrowheads).

Figure 2 Macroscopic and microscopic findings. A: Macroscopic view of a low-grade appendiceal mucinous neoplasm (LAMN), showing cystic dilation of the appendix filled with mucinous content; B: Microscopic view of a LAMN with hematoxylin & eosin staining (× 40 magnification), showing a mucosal surface lined by a single layer of mucin-producing columnar epithelium without high-grade cytologic atypia; C: Additional microscopic view of a LAMN with hematoxylin & eosin staining (× 40 magnification), highlighting features similar to panel B.

Figure 3 Immunohistochemical findings. A: Immunohistochemical staining for cytokeratin 20, showing diffuse positivity on the mucosal surface layer (× 40 magnification); B: Immunohistochemical staining of cytokeratin 7, showing partial positivity on the mucosal surface layer (× 40 magnification); C: Immunohistochemical staining for mucin 5AC, showing partial positivity on the mucosal surface layer (× 40 magnification).

Figure 4 Decision tree for positive surgical resection margins. CRS: Cytoreductive surgery; HIPEC: Hyperthermic intraperitoneal chemotherapy; PMP: Pseudomyxoma peritonei.

Figure 5  Proposed algorithm for the treatment strategy of appendiceal mucinous neoplasms.