Neoplasia: Definition and Risk Factors

Neoplasia Definition and Risk Factors

• Neoplasia is an uncontrolled abnormal growth of cells or tissues in the body.
• Risk factors include:
  • Genetic predisposition: inherited genetic mutations or familial cancer syndromes.
  • Environmental exposures: exposure to carcinogenic agents, such as tobacco smoke, UV radiation, and ionizing radiation.
  • Infectious agents: chronic infections with certain viruses, bacteria, or parasites, such as HPV and cervical cancer.
  • Age and gender: advancing age is a significant risk factor, with most cancers increasing with age.

Cellular Characteristics of Malignant Neoplasms

• Variation in size
• High N/C ratio
• Cellular pleomorphism
• Nuclear pleomorphism
• High mitotic activity
• High chromatin nucleus
• Loss of polarity

Neoplasia Behavior and Classification

• Benign: well-differentiated, locally non-invasive, and non-metastatic.
• Malignant: moderately differentiated, locally invasive, and metastatic.

Types of Neoplasms

Benign Neoplasms

• Connective tissue:
  • Lipoma (adipose tissue)
  • Fibroma (fibrous tissue)
  • Chondroma (cartilage)
  • Osteoma (bone tissue)
• Epithelial tissue:
  • Papilloma (surface epithelium)
  • Adenoma (glandular epithelium)

Malignant Neoplasms

• Connective tissue:
  • Sarcoma (e.g. liposarcoma, fibrosarcoma, chondrosarcoma, osteosarcoma)
• Epithelial tissue:
  • Carcinoma (e.g. squamous cell carcinoma, basal cell carcinoma, adenocarcinoma)

Specific Types of Neoplasms

Squamous Cell Papilloma

• Benign nature
• Papillary architecture
• Koilocytosis: presence of enlarged, irregularly shaped squamous epithelial cells with perinuclear halos, often indicative of HPV infection.

Columnar Cell Papilloma

• Typically found in the subareolar region of the breast, particularly in the large lactiferous ducts near the nipple.

Follicular Thyroid Adenoma

• Encapsulation: surrounded by a fibrous capsule that separates them from the surrounding thyroid tissue.
• Causes: iodine deficiency, radiation exposure.

Fibroadenoma

• Benign breast tumors
• Composed of both glandular and fibrous tissue
• Causes: hormonal influence (estrogen and other hormonal factors)

Cystadenoma

• Benign cystic tumors
• Arise from glandular epithelial cells
• Characterized by the presence of cystic spaces filled with fluid (usually serous fluid)

Neurofibroma

• Originate from Schwann cells
• Distributed along peripheral nerves throughout the body
• Can be benign or malignant (neurofibrosarcoma)

Lipoma

• Benign
• Well-bounded
• Non-invasive
• Closely resembles the tissue of origin (fat)

Basal Cell Carcinoma

• Typically begins as a nodule, progresses to ulceration or crusting, and may subsequently invade deeper layers of the skin if left untreated.
• Causes: UV radiation exposure.

Squamous Cell Carcinoma

• Often exhibits keratinization
• Potential for metastasis
• Causes: UV radiation exposure, chronic skin damage.

Adenocarcinoma

• Causes: chronic inflammation, prolonged exposure to irritants, infections, or inflammatory conditions.
• Examples: colon adenocarcinoma, pancreatic adenocarcinoma.

Osteosarcoma

• Often causes extensive destruction of the affected bone
• Causes: bone dysplasias and growth disorders, such as hereditary multiple exostoses (osteochondromatosis).

Test your knowledge of neoplasia, including its definition, genetic predisposition, environmental exposures, and infectious agents that contribute to its development. Assess your understanding of the risk factors associated with this abnormal growth of cells or tissues.