Pathology: Neoplasms and Cancer

Definition and Classification

• Neoplasia refers to the abnormal and uncontrolled growth of cells, leading to the formation of a neoplasm (tumor)
• Neoplasms can be benign (non-cancerous) or malignant (cancerous)

Types of Neoplasms

• Benign neoplasms:
  • Typically do not invade surrounding tissues or metastasize
  • Can still cause symptoms due to their size or location
  • Examples: uterine fibroids, melanocytic nevus (moles)
• Malignant neoplasms (cancer):
  • Can invade surrounding tissues and metastasize to distant sites
  • Can be fatal if left untreated
  • Examples: carcinoma, sarcoma, lymphoma, leukemia

Characteristics of Neoplastic Cells

• Loss of cellular regulation: Neoplastic cells ignore normal growth signals and continue to proliferate uncontrollably
• Genetic mutations: Neoplastic cells often have genetic abnormalities that contribute to their uncontrolled growth
• Dysregulation of apoptosis: Neoplastic cells may resist programmed cell death (apoptosis)
• Abnormal cell morphology: Neoplastic cells often exhibit altered size, shape, or structure

Neoplasm Development and Progression

• Multistep hypothesis: Neoplasia develops through a series of genetic mutations and epigenetic changes
• Tumor initiation: Initial mutation or exposure to carcinogen
• Tumor promotion: Stimuli that enhance neoplastic growth, such as hormones or growth factors
• Tumor progression: Neoplasm becomes more aggressive and invasive over time

Definition and Classification

• Neoplasia is the abnormal and uncontrolled growth of cells, resulting in a neoplasm (tumor)
• Neoplasms can be classified as either benign (non-cancerous) or malignant (cancerous)

Types of Neoplasms

• Benign Neoplasms
  • Do not invade surrounding tissues or metastasize
  • Can cause symptoms due to size or location
  • Examples include uterine fibroids and melanocytic nevus (moles)
• Malignant Neoplasms (Cancer)
  • Invade surrounding tissues and metastasize to distant sites
  • Can be fatal if left untreated
  • Examples include carcinoma, sarcoma, lymphoma, and leukemia

Characteristics of Neoplastic Cells

• Loss of Cellular Regulation: Neoplastic cells ignore normal growth signals and proliferate uncontrollably
• Genetic Mutations: Neoplastic cells often have genetic abnormalities contributing to uncontrolled growth
• Dysregulation of Apoptosis: Neoplastic cells resist programmed cell death (apoptosis)
• Abnormal Cell Morphology: Neoplastic cells exhibit altered size, shape, or structure

Neoplasm Development and Progression

• Multistep Hypothesis: Neoplasia develops through a series of genetic mutations and epigenetic changes
• Tumor Initiation: Initial mutation or exposure to carcinogen
• Tumor Promotion: Stimuli enhancing neoplastic growth, such as hormones or growth factors
• Tumor Progression: Neoplasm becomes more aggressive and invasive over time