Cell Growth and Neoplasia

Question 1

Review key concepts of normal cell growth and differentiation control.

Answer 1

Active cell growth is a hallmark of normal development (morphogenesis): single cell–> complex multicellular organism with highly specialized tissues functioning in an integrated manner. Cells proliferate, migrate, differentiate, change their relationship to neighboring cells, undergo apoptosis.

Adulthood (development is fully complete), diminution of active cell growth, growth is under tight regulatory control.
Homestatic adult tissues:
-Non-dividing tissues (little no/proliferation, i.e. brain)
-Quiescent tissues (proliferate only in response to stimuli, e.g. liver)
-Continuously dividing tissue (e.g. gut)

Question 2

Hypertrophy

Answer 2

Increase in cell size, usually in response to some stimulus, can be physiologic or pathologic

Question 3

Hyperplasia

Answer 3

Increase in cell number, often in response to stimulus, can be physiologic, or pathologic, may predispose neoplasia

Question 4

Metaplasia

Answer 4

Change from one benign, differentiated cell type to another, usually in response to injury, may predispose neoplasia.

Question 5

Neoplasia

Answer 5

Autonomous, progressive cell growth, involving clonal cell population

Question 6

Tumor

Answer 6

Latin for swelling, synonymous with neoplasia

Question 7

Benign Neoplasia

Answer 7

Biologic behavior:

• Doesn’t invade or metastasize
• Causes injury largely by compression/interference in function of adjacent structures

Gross pathologic features:

• Circumscribed/encapsulated
• Necrosis uncommon

Microscopic pathologic features:

• generally relatively well differentiated
• generally low rate of cell turnover
• ctyological uniformity
• boundary between tumor and adjacent tissue generally maintained

Tissue of origin:
Epithelial: adenoma, papilloma
Mesenchymal: osteoma, chondroma, fibroma

Clinical correlates: Tx is excision or surgical resection alone, may recur if incompletely excised, generally do not profress to malignancy (except with premalignant neoplasms)

Question 8

Malignant neoplasia

Answer 8

Biologic behavior:

• Invade and mestastsize (cancer!)
• Cause injury by both local tissue destruction and distant dissemination and tissue destruction

Gross pathologic features:

• Invasive into adjacent tissue
• Necrosis common

Microscopic pathologic features:

• Variable differentiation, generally less than benign tumors.
• Generally high rate of cell turnover (proliferation and apoptosis)
• Cytologic pleomorphism (cells different from each other)
• Generally loss of boundary between tumor and adjacent tissue

Tissue of origin:
-Epithelial: Carcinoma
Mesenchymal: Sarcoma
Hematopoietic: Lymphoma, Leukemia (bone marrow origin)

Question 9

Malignant neoplasia epidemiology

Answer 9

1 in 2 american will get cancer, 1 in 5 will die from it.

Question 10

Malignant neoplasia etiology

Answer 10

• Age
• Lifestyle/environment (tobacco, alcohol)
• Occupational hazards/chemical carcinogens
• Radiation
• Infection
• Inflammation (e.g. ibd and colorectal cancer)
• genetic factors

Question 11

Malignant neoplasia pathobiology

Answer 11

• Evading apoptosis
• Self-sufficiency in growth signals
• Insensitivity to anti-growth signals
• Tissue invasion and mestasis
• limitless replicative potential
• sustained angiogenesis

Question 12

Histological grade

Answer 12

Degree of tumor histologic differentiation (ie. resemblance of normal tissue counterpart)
Low grade: more differentiation/greater resemblance to norm
High grade: less differentiation/less resemblance to normal

-Varies by tumor type

Question 13

Tumor stage

Answer 13

Critical prognositc factor: grade is based on how much metastasis has occurred. Tumor stage I (lowester = 93% survival rate at 5 years) to Tumor stage V( 8% survival rate at 5 years)