**Note:** Peritoneal spread is common in appendiceal tumors and is coded as 30 if limited to the peritoneum. Peritoneal implants involving abdominopelvic organs, such as the serosa of the small or large bowel and the surface of the ovary, spleen, or liver, should be coded as 30, regardless of whether implants demonstrate infiltration of underlying tissue, manifested as invasion. Nonperitoneal metastasis, such pleuropulmonary involvement is rare and would be coded as 50.
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