Cell Growth Disturbances and Neoplasia

Disturbance of Cell Growth and Neoplasia

• Cell Growth Disturbances: Deviation in cell size and/or number, encompassing a range of pathological conditions.
• Conditions range from absence of tissue development (agenesis) to unregulated growth (neoplasia).
• Types of Cell Growth Disturbances:
  • Non-Cancerous Disturbances:
    • Developmental Disorders (Hereditary & Congenital): Abnormal germ cell (sperm or ovum), or congenital abnormalities arising after fertilization. Includes conditions like agenesis, aplasia, atresia, and hypoplasia.
    • Acquired Adaptive Disorders: Changes in cell size or number due to adaptation. Includes hypertrophy, hyperplasia, and metaplasia; as well as atrophy.
    • Acquired Non-Adaptive Disorders: Dysplasia and anaplasia (disorganization and abnormality in cell structure).
  • Cancerous Disturbances (Neoplasia): Uncontrolled, abnormal cell growth and multiplication.

Causes of Congenital Anomalies

• Both genetic and environmental factors are responsible.
• Some inherited disorders may or may not have a known genetic history.
• Nutritional factors
• Exposure to radiation
• Chemical exposure (drugs, etc.).
• External (environmental) agents acting on the developing fetus. These are known as teratogens.
• Infections, potentially transmitted from the mother during early gestation, can be a concern.
• Increased maternal age is a risk factor.

Specific Developmental Disturbances

• Agenesis: Complete absence of an organ or tissue.
• Aplasia: Failure of an organ or tissue to develop, potentially with abnormal tissue growth in the affected area.
• Hypoplasia: Underdevelopment or incomplete development of a tissue or organ.
• Atresia: Failure of canalization of a hollow organ (absence or closure of a normal opening).

Acquired Adaptive Disturbances

• Atrophy: Decrease in size and weight of a tissue or organ due to decreased cell size/number. Can be physiological (senility, etc) or pathological.
• Hypertrophy: Increase in size and weight of a tissue or organ due to increased cell size only. Can be adaptive compensatory response or hormonal.
• Hyperplasia: Increase in the number of cells in a tissue or organ. Can be Physiological (compensatory, hormonal) or Pathological (irritative).
• Metaplasia: Adaptive substitution of one type of adult cell for another, potentially in response to environmental factors. Can be epithelial (squamous or glandular) or connective tissue (osseous or cartilaginous).

Acquired Non-Adaptive Disturbances

• Dysplasia: Abnormal, disorganized cellular growth in tissues, commonly associated with epithelium. Often considered precancerous.
• Anaplasia: Severe cellular dedifferentiation; loss of cellular structure and function; often considered a hallmark of severe cancers.

Neoplasia (Cancerous Disturbances)

• Neoplasia: Uncontrolled, abnormal cell growth and multiplication, forming a new tissue.
• Oncology: The scientific study of neoplasms or tumors.
• Factors of carcinogenesis (oncogenesis): Genetic predisposition, environmental factors (chemicals,radiation,etc.), infections, and others.
• Types of carcinogens: Chemical, physical (radiation), viral, and others.
• Factors influencing malignant tumor growth or spread can include: Age, hormones, race, diet, trauma, personal habits.

Classification and Nomenclature of Tumors

Types of tumors are described according to:

• • Morbid anatomy (clinical classification).
• • Degree of differentiation, or tumor grade.
• • Origin of cell type, or histogenetic classification
• • Specific cell products/markers.

Microscopic Characteristics of Benign and Malignant Tumors

• Benign Tumors: Cellular uniformity, normal cytology, and little or no mitotic activity.
• Malignant Tumors: Cellular variability (pleomorphism), high mitotic activity, and loss of differentiation, high N:C ratio (nuclear to cytoplasm ratio).

Additional Important Characteristics of Cancer Development

• Local spread: cancer cells spreading to surrounding tissues.
• Metastasis: cancer cells spreading to distant sites via lymphatic or blood vessels.