Chapter 5 Hyperplasias and Neoplasms Review of Structure and Function All cells develop from the fertilized ovum Review of Structure and Function Cell division continues into specialized cells including: Labile Cells Stable Cells Epithelial Cells Connective Tissue Cells Muscle Cells Nervous tissue Cells Hyperplasia and Hypertrophy Hyperplasia and hypertrophy are exaggerated responses to a growth stimulus This can be a normal response to the bodys demands. Metaplasia and Neoplasia Metaplasia is the replacement of one tissue type with another. This can be a normal response, or a pathologic change. Neoplasia is similar to hyperplasia in that they are both increased cell proliferation The difference is neoplasia is cell proliferation in the absence of a stimulus. Hyperplasia and Neoplasia The masses produced by these processes cannot be distinguished from one another without a histological examination. Treatment for each is vastly different. Remember, neoplasias are autonomous growth, while hyperplasias will stop growing once the stimulus is removed. Classification of Neoplasms Typically put into one of three categories Benign Malignant Uncertain malignant potential Benign Neoplasms Benign neoplasms generally are localized, and remain in the tissue in which they originated These are a single mass discrete from the surrounding tissue. Benign Neoplasms They usually have a fibrous rim or capsule around them, which makes them easier to excise. The cells closely resemble the cells of origin Malignant Neoplasms Malignant neoplasms are more likely to spread to entirely different sites, or invade nearby structures. Metastasis often occurs through the lymph nodes.