Introduction to Neoplasia Major Topics for Discussion

Definition of neoplasia Benign neoplasms Malignant neoplasms Spread of neoplastic cells (metastasis) Clinical evaluation: grading and staging Epidemiology Oncogenes and tumor suppressor genes

Neoplasia

Clonal proliferation of cells Autonomous growth - uncoordinated Derived from cells with proliferative

capacity (active cell cycle) Results from alterations in DNA Some resemblance to cell of origin

Classification

Benign

vs

Malignant

Benign Neoplasms

Grow slowly Do not invade adjacent tissues or

metastasize (spread to distant sites) Often are encapsulated Closely resemble cell of origin

(differentiated) Uncommonly cause patient death

Uterine Leiomyoma (benign smooth muscle cell tumor)

Benign Gastrointestinal Polyp

Benign Brain Tumor (Meningioma)

Malignant Neoplasms

Grow more rapidly Invade adjacent tissues and have

potential to metastasize Not encapsulated Less-closely resemble cell of origin More-likely to cause patient death

Adenocarcinoma of Colon

Adenocarcinoma of Uterus

Squamous Cell Carcinoma

Nomenclature

General rules cell type + “oma” = benign neoplasm

cell type + “carcinoma” =

malignant neoplasm of epithelial origin

cell type + “sarcoma” =

malignant neoplasm of mesenchymal origin

Examples (Benign & Malignant)

Chondroma & condrosarcoma Lipoma & liposarcoma

Adenoma & adenocarcinoma (of breast) Papilloma & squamous cell carcinoma

Exceptions to Rules

Malignant tumors include:

Teratoma

Seminoma

Lymphoma

Melanoma

These neoplasms have an “oma” suffix, but they are malignant.

Morphology of Neoplasms Differentiation – degree of resemblance to

normal cell of origin Anaplasia – lack of differentiation Pleomorphism – variation in cell size and

nuclear appearance Mitotic rate – reflects proliferative rate Necrosis – outgrow blood supply

Gross & Microscopic Features

Benign Meningioma

Malignant Melanoma

Benign Neoplasm of

cartilage

Normal Cartilage

Malignant Chondrosacrcoma

Squamous Cell Carcinoma(note the keratin “pearls”)

Spread of Neoplasms

Carcinoma in situ (no invasion of the basement membrane)

Local invasion Seeding of body cavities (carcinomatosis)

Distant metastasis Lymphatic spread Hematogenous spread

cervical biopsy shows carcinoma in-situ - CIS

Invasive Cervical Squamous Cell Carcinoma

Malignant Melanoma (radial growth phase)

Bone Metastases of Malignant Melanoma

Metastatic Liver Cancer

Peritoneal Carcinomatosis - Widely Disseminated Cancer

Hematogenous Spread

Lymphatic Spread

Mechanisms of Metastatis Altered Cell

Adhesion Altered Cell

Motility Hydrolytic

enzymes Invasion

Grading and Staging

Used to predict the behavior of neoplasms (prognosis) and determine appropriate therapy

Grading – assessment of degree of differentiation and proliferative capacity

Staging – assessment of tumor size and extent of spread locally and distantly

Epidemiology

20% of total mortality in the US Epithelial cancers (lung, colon, breast,

prostate) are most common in adults Leukemia, lymphoma, CNS neoplasms

are most common in children Geographic differences in incidence Environmental associations

(carcinogens)

Cancer Incidence in US Males

Cancer Incidence US Females

Neoplasia is a Genetic Disease

Oncogenes

Tumor suppressor genes

Chromosomal Translocation and Neoplasia

Retinoblastoma and Rb Tumor Suppressor Gene Mutations

Path Key Words Adenocarcinoma Adenoma Carcinoma in situ Chondroma Chondrosarcoma Grading Hepatoma Leukemia Lipoma

Melanoma Metastasis Peritoneal

carcinomatosis Squamous cell

carcinoma Staging Teratoma Transitional cell

carcinoma