Anatomic pathology selected abstracts
July 2023—High-grade appendiceal mucinous neoplasm is a relatively recent term that describes a rare epithelial neoplasm of the appendix that demonstrates pushing-type invasion but high-grade cytologic atypia. Because it has been understudied, the authors conducted a multi-institutional retrospective study to describe the clinicopathologic features of high-grade appendiceal mucinous neoplasm (HAMN). They reviewed the clinical and histologic features of 35 HAMNs and the molecular features of eight of the cases. Patients were an average of 57 years old and most commonly presented with abdominal or pelvic pain. Histologically, 57 percent of the tumors showed widespread high-grade features.