12: Neoplasms

Neoplasia

New tissue growth or mass

Term for a malignant neoplasia

Cancer

How does neoplasia become cancer

Irreversible mutations

How do normal cells replicate

In response to physiologic stimulus in a controlled manner

How do neoplastic cells replicate

With no regard for physiologic control, becoming excessive and uncoordinated

Types of non-neoplastic proliferations

• Hamartoma

• Choristoma

Hamartoma

Non-neoplastic overgrowth of mature tissue in a normal location

Choristoma

Non-neoplastic proliferation of normal tissue an an ectopic location

Normal, injurious changes that can be pre-neoplastic changes

• Hyperplasia

• Hypertrophy

• Atrophy

• Metaplasia

• Dysplasia (disorganized hyperplasia)

Features used to grossly estimate if a tumor is benign or malignant

Differentiation and anaplasia

Differentiation

The extent to which a cell looks like and functions like a normal cell

Anaplasia

A lack of differentiation; key marker for malignancy

Features of anaplasia

• Pleiomorphism

• Abnormal nuclei

• Mitotic figures

• Loss of polarity

• Loss of characteristic features

• Tumor giant cell formation

Pleiomorphism

Variation in size and shape of cells and nuclei

Features of abnormal nuclei

• Hyperchromic

• Large nuclei

• May have prominent nucleoli

What is indicated by mitotic figures

Increase in mitotic activity

What is a tumor giant cell

A large cell with multiple nuclei

What does it mean that a cell has lost polarity

You can no longer tell which side is up or down

How does a benign tumor grow

Expansion with maintenance of boundaries

How does a malignant tumor grow

Invading and infiltrating adjacent tissues with no regard for self containment

For which type of tumor is excision typically curative

Benign

What characteristic instantly means a tumor is malignant

Metastasis

Metastasis

Spread of tumor to a site separate from the primary mass

Pathways for metastasis

• Direct implantation

• Blood

• Lymph

Which type of vessel more easily accessed for metastasis

Veins

Components of a tumor

Stroma and parenchyma

Which tumor component determines tumor type

Parenchyma

Types of parenchymal cells

Epithelial and mesenchymal

Epithelium

Cells lining body surfaces or cells that make up glands

Mesenchymal cells

Any sort of CT: bone, fat, collagenous tissues

• Also endothelium :((

Suffix for benign tumors

-oma

Suffix for malignant epithelial masses

-carcinoma

Suffix for malignant mesenchymal masses

-sarcoma

Common site for mixed tumors

Mammary tumors

Mixed tumor with cells from multiple embryonic germ layers

Teratoma

Blastoma

Mass of embryonic cells resulting from inherited mutations

Example cells from neuroectodermal origin

• Melanocytes

• Adrenal medulla cells (chromaffin cells)

Benign and malignant tumors of melanocytes

• Melanoma or melanocytoma

• Malignant melanoma

Benign and malignant tumors of chromaffin cells

• Pheochromocytoma

• Malignant pheochromocytoma

Benign and malignant tumors of lymphocytes

• They are never benign

• Lymphoma or malignant lymphoma or lymphosarcoma

Benign functional tumor of the pancreatic islets

Insulinoma

Tumors of monocyte origin in the tissues (hint: what does a monocyte become once it leaves the blood?)

• Histiocytoma

• Histiocytic sarcoma

  • Monocytes become macrophages in the tissues!

Why are most CNS tumors considered malignant

Their location causes a lot of damage, whether the tumor is benign or malignant

Benign tumors of surface epithelium, also called warts

Papillomas

Proliferation of the mucosa, often attached by a stalk

Polyp