High Grade Appendix Mucinous Adenocarcinoma

**Semantic type:** Neoplastic Process

**Definition:** A mucinous adenocarcinoma that arises from the appendix. The malignant cells are numerous and exhibit high grade dysplasia. It may be associated with pseudomyxoma peritonei, but unlike the low grade mucinous neoplasm, it invades other organs and metastasizes to distant anatomic sites.