MUC5AC and pseudomyxoma peritonei: Therefore, this case further establishes the capacity of appendiceal primary neoplasia to colonize the endometrial surface (presumably via transit through the fallopian tubes), as both acellular mucin and neoplastic mucinous epithelium have previously rarely been observed to involve the endometrial surface in the context of an appendiceal mucinous neoplasm with pseudomyxoma peritonei [9–11].