Neoplasia 1: Important Definitions and Cytological Features of Malignancy

Define Neoplasia

• a process of ‘new growth’

• continued proliferation (expands beyond normal anatomical boundaries)

Describe Neoplasia (what is it a result of, what is it unresponsive to, and what does it result in)

• result of irreversible genetic change

• unresponsive to intrinsic (the cell itself) or extrinsic (surrounding normal cells) growth control signals

• results in macroscopic or microscopic neoplasm

List two other common terms of neoplasia

• Tumor = swelling

• Cancer = crab-like infiltrative appearance

Define ‘Onco’ and Define Oncology

• Onco = mass/tumor

• Oncology = study of neoplasia

What kind of growths do the generic terms ‘Neoplasm’ and ‘tumor’ describe?

Benign and Malignant

Is cancer benign of malignant?

malignant

Define benign (type of growth, what the growth does not do, curable? fatal?) and list the exceptions for it

• HARMLESS growth

• does not:

  • invade surrounding tissue

  • spread to new anatomic locations

• frequently curable

• rarely fatal (if treated appropriately)

• Exceptions:

  • critical space-occupying lesion (cranial cavity or spinal canal)

  • non-invasive but compressive intracranial/CNS tumors

Define Malignant (type of growth, where does it invade and spread, is it fatal?)

• HARMFUL growth

• invades surrounding tissues

• spreads to distant anatomical locations (metastasis)

• frequently fatal

why are malignant growths usually fatal?

compromise critical body functions

Are all swellings/masses neoplasms?

NO

• they can also be abscesses (inflammatory and necrotic processes)

What kind of process is tumor development?

stepwise process

What are preneoplastic changes a response to? Can preneoplastic changes resolve?

• response to:

  • physiological demands

  • injury

  • chronic inflammation

  • irritation

• resolve if cause is removed

List preneoplastic changes

• Hypertrophy

• Hyperplasia

• Metaplasia

• Dysplasia

• Anaplasia/Atypia

What does Anaplasia/Atypia indicate?

indicator of irreversible progression to neoplasia

Define Hypertrophy, Hyperplasia, Metaplasia, Dysplasia and Anaplasia/Atypia

• Hypertrophy

  • increase in size of individual cells

• Hyperplasia

  • increase in number of cells

• Metaplasia

  • transformation of one differentiated type to another cell type

• Dysplasia

  • abnormal growth pattern with disordered arrangement of cells

• Anaplasia/Atypia

  • loss of cellular differentiation

List tumor types / cell of origin

• Mesenchymal tumors

  • include “round cell” hematopoietic/lymphoid

• Epithelial Tumors

• Tumors of Neural Crest Cells

• Tumors of Uncertain Origin

• Mixed Tumors

• Tumor-like Lesions

Describe Mesenchymal Tumors (what tissue do they arise from, what are they composed of, how are they arranged, what are they called if they are benign or malignant)

• arise from embryonic mesodermal tissue

  • CT, adipose, cartilage, bone, epithelium + related tissues, muscle, etc)

• composed of spindle-shaped cells

• arranged in streams, bundles, and fasicles

• Benign = cell type plus ‘oma’

• Malignant = cell type plus ‘sarcoma’

What other two types of tissue do mesenchymal tumors “technically” include?

Hematopoietic and lymphoid tissue

Describe round cell tumors (mesenchymal tumor) (what tissue do they arise from, how are they arranged)

• hematopoietic and lymphoid tissues

• arranged in solid sheets

What is a lymphoma

• type of round cell tumor

• tumor of lymphoid cells

  • B or T lymphocytes derived

Define leukemia

• type of round cell tumor

• caused by abnormal blood cells/precursors in blood and bone marrow

  • presence of neoplastic cells in circulation

What are the benign counterparts for lymphomas and leukemias?

• there are NO benign counterparts

• all considered MALIGNANT

How are mast cell tumors (MCTs) distinguished?

low grade vs high grade