Appendiceal Neoplasms: Tumors or cancer of the APPENDIX.Appendix: A worm-like blind tube extension from the CECUM.Cecal Diseases: Pathological developments in the CECUM.Mucocele: A retention cyst of the salivary gland, lacrimal sac, paranasal sinuses, appendix, or gallbladder. (Stedman, 26th ed)Appendectomy: Surgical removal of the vermiform appendix. (Dorland, 28th ed)Pseudomyxoma Peritonei: A condition characterized by poorly-circumscribed gelatinous masses filled with malignant mucin-secreting cells. Forty-five percent of pseudomyxomas arise from the ovary, usually in a mucinous cystadenocarcinoma (CYSTADENOCARCINOMA, MUCINOUS), which has prognostic significance. Pseudomyxoma peritonei must be differentiated from mucinous spillage into the peritoneum by a benign mucocele of the appendix. (Segen, Dictionary of Modern Medicine, 1992)Appendicitis: Acute inflammation of the APPENDIX. Acute appendicitis is classified as simple, gangrenous, or perforated.Cystadenoma, Mucinous: A multilocular tumor with mucin secreting epithelium. They are most often found in the ovary, but are also found in the pancreas, appendix, and rarely, retroperitoneal and in the urinary bladder. They are considered to have low-grade malignant potential.