LM 7.4: Benign vs. Malignant

Question 1

what are the four features you can use to distinguish between benign and malignant tumors?

Answer 1

1. degree of differentiation
2. growth rate
3. local invasion
4. metastasis

Question 2

what is differentiation?

Answer 2

extent to which neoplastic cells resemble comparable normal cells, morphologically and functionally

describes how much or how little tumor tissue looks like the normal tissue it came from

well-differentiated cancer cells look more like normal cells

Question 3

what is the degree of differentiation of benign neoplasms?

Answer 3

well differentiated!

aka they look like normal cells

Question 4

what is the degree of differentiation of malignant neoplasms?

Answer 4

malignant neoplasms range from well differentiated to anaplastic

in between the two extremes are tumors that are referred to as moderately well differentiated

Question 5

what is anaplasia?

Answer 5

lack of differentiation

anaplasia is the hallmark of malignancy!

Question 6

what are the characteristics of anaplasia?

Answer 6

• pleomorphism (variation in size and shape)
• mitoses
• loss of polarity
• abnormal nuclear morphology

Question 7

what is the abnormal nuclear morphology seen in anaplasia?

Answer 7

hyperchromasia (dark chromatin)

high N/C ratio

irregular nuclear shape

large nucleoli

Question 8

what are the functional changes that happen in well differentiated vs. poorly differentiated tumors?

Answer 8

well differentiated tumors retain the functional capabilities found in its normal tissue counterpart

poorly differentiated and anaplastic carcinomas are unable to perform their normal functions –> sometimes abnormal functions emerge that cause abnormal production of proteins or hormones

Question 9

what is the growth rate of benign tumors?

Answer 9

slow growth rate

Question 10

what is the growth rate of malignant tumors?

Answer 10

variable growth rate

growth rate correlates with degree of differentiation

Question 11

what is doubling time?

Answer 11

the total cell cycle time for many tumors is equal to corresponding normal cells

Question 12

what is local invasion for benign tumors?

Answer 12

benign tumors grow as cohesive expansile masses that remain localized to their site or origin

because they grow slowly, they often develop a rim of compressed connective tissue called a capsule

Question 13

what is local invasion for malignant tumors?

Answer 13

malignant tumors grow by infiltration, invasion and destruction of the surrounding tissue

they’re poorly demarcated from surrounding tissue

next to metastasis, invasion is most reliable feature of malignancy!

Question 14

what is metastasis?

Answer 14

the spread of tumor to sites that are physically discontinuous with the primary tumor

metastasis means 100% that a tumor is malignant because by definition, benign tumors don’t metastasize

Question 15

which cancers can metastasize?

Answer 15

all cancers can metastasize except CNS gliomas and basal cell carcinomas of the skin

Question 16

what are the routes of metastasis?

Answer 16

1. seeding of body cavities and surfaces like the ovaries and appendix
2. lymphatics: follows the natural course of lymphatic drainage
3. hematogenous spread: typical of sarcomas but also seen with carcinomas

Question 17

what is a sentinel lymph node?

Answer 17

the first node in a regional lymphatic basin that receives flow from the primary tumor

Question 18

carcinoma vs sarcoma

Answer 18

a carcinoma forms in the skin or tissue cells that line the body’s internal organs, such as the kidneys and liver

a sarcoma grows in the body’s connective tissue cells, which include fat, blood vessels, nerves, bones, muscles, deep skin tissues and cartilage

carcinomas are the most common type of cancer.