当然，肿瘤有良性和恶性之分，尽管它们的区别不总是很明显的。图示小肠浆膜表面的良性肿瘤－脂肪瘤，具有良性瘤特点：周围局限、生长缓慢、和与起源组织（脂肪组织）很相似。
Of course, neoplasms can be benign as well as malignant, though it is not always easy to tell how a neoplasm will act. Here is a benign lipoma on the serosal surface of the small intestine. It has the characteristics of a benign neoplasm: it is well circumscribed, slow growing, and resembles the tissue of origin (fat).