Part 18: Classifications of Neoplasms

What are the 4 ways in which neoplasms are classified?

1. Biological Classifications: Benign vs Malignant Tumors

2. Site of origin

3. Tissue of origin

4. Histological origin

Distinct characteristic of benign tumors?

surrounded by a distinct capsule of fibrous tissue, which facilitates surgical removal if necessary

What are the 4 characteristics of a benign tumor?

1. slow growing

2. encapsulated

3. grow by direct extension

4. USUALLY not fatal

Characteristics of a malignant tumor

1. usually faster growing

2. progressively less cellular differentiation

3. grow by invasion and metastases

4. fatal unless treated

if it ends in -oma, the tumor is usually (benign/ malignant)

benign

what is meant by site of origin?

e.g. breast, prostate, lung etc.

3 types of cancers and their tissues of origin

1. carcinoma→ epithelial tissues i.e. endodermal & ectodermal tissues

2. sarcoma→ mesenchymal tissues (except blood) & mesodermal tissues

3. lymphomas & leukemias→ blood and lymphatic tissues

4. misc.

Which tissue of origin classification is the most common?

carcinoma

term. epithelial

def. tissues on the surface and leading to the outer surface. And organs and lining of organs that are glandular.

endodermal tissues

tissues that develop into internal structures such as stomach and intestines

ectodermal tissues

tissues that develop into external structures such as skin

carcinomas most commonly spread thru

lymphatics (fyi: since there are no blood vessels)

mesenchymal cells

fleshy/ connective tissues

mesodermal tissues

tissues that develop into supporting structures such as: bone, muscle, fat

sarcomas most commonly spread thru

the blood

sarcomas typically mets to

the lungs

histological origin means

cell origin. e.g. squamous cell

squamous cell carcinoma of the tongue

what are the classifications?

squamous cell → histological origin

carcinoma → tissue of origin

tongue → site of origin

adenocarcinoma of the pancreas

what are the classifications?

aden/o → histological origin

carcinoma → tissue of origin

pancreas → site of origin

sarcomas may also carry a __ prefix

histological

osteosarcoma

give the classification

osteo → histological origin & site of origin

sarcoma → tissue of origin

chondrosarcoma

give the classification

chondro→ histological origin & site of origin

sarcoma → tissue of origin

liposarcoma

give the classification

lipo→ histological origin & site of origin

sarcoma → tissue of origin

How is important is establishing a pathological diagnosis?

It is so important that treating the cancer without knowing the pathology would be of little use

True or False: Pathological confirmation is the most valuable, clinical suspicion is not valuable at all

False; e.g. carcinoma of the lung is a disease that can be diagnosed without a tissue sample

but considering there are 4 types of lung cancer cells, pathology is important too