Benign Vs Malignant Tumors
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You are here: Home » Pathology Notes » Benign Vs Malignant Tumors
| | Benign | Malignant |
| Differentiation and Anaplasia (refers to parenchymal cells) | Well differentiated; structure may be typical of tissue of origin | Some lack of differentiation with anaplasia; structure is often atypical; anaplastic cells display pleopmorphism, the nuclei are hyperchromatic and large (nuclear-cytoplasmic ratio may be 1:1 instead of 1:4 or 1:6) |
| Rate of Growth | Usually progressive and slow; may come to a standstill or regress; mitotic figures are rare and normal | Erratic and may be slow to rapid; mitotic figures may be numerous and abnormal |
| Local Invasion | Usually cohesive and expansile, well-demarcated masses that do not invade or infiltrate the surrounding normal tissues | Locally invasive, infiltrating the surrounding normal tissues; sometimes may seem cohesive and expansile but with microscopic invasion |
| Metastasis | Absent | Frequently present; the larger and less differentiated the primary, the more likely are metastases |
-The better the differentiation of the cell, the more completely it retains the functional capabilities of its normal counterparts.
-The more rapidly growing and anaplastic a tumor, the less likely it is to have specialized functional activity.
-When dysplastic changes are marked and involve the entire thickness of the epithelium, the lesion is referred to as carcinoma in situ, a preinvasive stage of cancer.
-The rate of growth of malignant tumors correlates with their level of differentiation.
-Most cancers take years to develop; very few, if any, develop suddenly (days to months).
-Rapidly growing malignant tumors often contain central areas of ischemic necrosis because the tumor blood supply, derived from the host, fails to keep pace with the oxygen needs of the expanding mass of cells.
-Some benign neoplasms have a fibrous capsule surrounding them but not all do. This capsule involves the stroma when present.
-Next to the development of metastases, local invasiveness is the most reliable feature that distinguishes malignant from benign tumors.
-Approximately 30% of new patients with solid tumors present with clinically evident metastases. Another 20% have occult metastases at the time of diagnosis.
-In general, the more anaplastic and the larger the primary neoplasm, the more likely is metastatic spread
-Cancers grow by progressive infiltration, invasion, destruction, and penetration of the surrounding tissue
Category: Pathology Notes
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