Pathology
Lecture 13 Neoplasia I – Nomenclature & Concepts
1) To understand the concept of neoplasia as autonomous growth of cells. Neoplasia
is the uncontrolled, disorderly proliferation of cells, resulting in a benign or malignant
tumor, or neoplasm.
2) To learn the fundamental differences, and host implications, of benign and
malignant neoplasms.
Benign tumors or neoplasms are usually well differentiated, closely resembling the
tissue of origin, grow slowly, and do not metastasize. They may also become
encapsulated. They are generally harmless but they may compress adjacent structures
and this may cause additional damage.
Malignant tumors or neoplasms (cancer) are capable of invasion (spread to adjacent
structures) and metastasis (implantation of the neoplasm into noncontiguous sites),
which is the defining characteristic of malignancy. They are often less differentiated
than benign tumors and exhibit pleomorphism, hyperchromatism, increased nuclear-
cytoplasmic ratio, and often have prominent nucleoli. They represent a danger to the
host and will result in death if not treated.
Feature Benign Malignant
Resemblance to mature cells Close Variable
Cell morphology Regular Variable
Nuclea/cytoplasmic ratio Low High
Biochemistry Complex Convergent
Rate of Growth Typically slow More rapid
Relation to surrounding tissue Expansion & compression Invasion & destruction
Dissemination No metastasis Metastasis
3) To become fluent in the general terminology of neoplasia (e.g., invasion,
metastasis, grading, and staging) as well as the specific nomenclature of
neoplasms. Tumors fall into three broad categories: tumors of one parenchymal cell
type, mixed tumors of more than one neoplastic cell type but derived from one germ
layer, and those composed of more than one cell type and more than one germ layer.
Generally: the suffix “-oma” refers to a tumor. Benign tumors end in “-oma” and
malignant tumors end in “-sarcoma” (mesenchymal origin) and “-carcinoma”
(epithelial origin) although some don’t have either suffix. Sarcomas have the cell of
origin as the stem while carcinomas must be learned individually.
Invasion: aggressive infiltration of adjacent tissues by a malignant tumor. Often
extends into lymphatics and blood vessels that may be carried to distant sites.
Metastasis: implantation in distal sites. Carcinomas tend to metastasize via lyphatics
while sarcomas metastasize via blood vessels.
Grading: a histopathologic evaluation of the lesion based on the degree of cellular
differentiation. Well 1→2→3 Poorly differentiated.
Staging: clinical assessment of the degree of localization or spread of the tumor
Composed of One Parenchymal Cell type
Tissue of Origin Benign Malignant
Mesenchymal Tumors
Connective tissue and derivatives Fibroma Fibrosarcoma
Lipoma Liposarcoma
Chondroma Chondrosarcoma
Osteoma Osteogenic sarcoma
Endothelial and related tissues:
blood vessels Hemangioma Angiosarcoma
lymph vessels Lymphangioma Lymphangiosarcoma
synovium Synovial sarcoma
mesothelium Mesothelioma
Brain coverings Meningioma Invasive meningioma
Blood cells and related cells
Hematopoietic cells Leukemias
Lymphoid tissue Malignant lymphomas
Muscle
Smooth Leiomyoma Leiomyosarcoma
Striated Rhabdomyoma Rhabdomyosarcoma
Epithelial Tumors
Stratified squamous Squamous cell Squamous cell or epidermoid
papilloma carcinoma
Basal cells of skin or adenexa Basal cell carcinoma
Epithelial lining ducts or glands Adenoma Adenocarcinoma
Papilloma Papillary carcinoma
Cystadenoma Cystadenocarcinoma
Respiratory passages Bronchogenic carcinoma
Bronchial “adenoma” (carcinoid)
Neuroectoderm Nevus Malignant melanoma
Renal epithelium Renal tubular Renal cell carcinoma
adenoma
Liver cells Liver cell adenoma Hepatocellular CA
Urinary tract epithelium Transitional cell Transitional cell CA
papilloma
Placental epithelium (trophoblast) Hydatidiform mole Choriocarcinoma
Testicular epithelium (germ cells) Seminoma
Embryonal carcinoma
Composed of More Than One Neoplastic Cell Type – Mixed Tumors
Tissue of Origin Benign Malignant
Salivary Glands Pleomorphic adenoma Malignant mixed tumor of
salivary origin
Breast Fibroadenoma Malignant cystosarcoma
phyllodes
Renal anlage Wilms’ tumor
Composed of More Than One Neoplastic Cell Type
Derived From More Than One Germ Layer – Teratogenous
Tissue of Origin Benign Malignant
Totipotential cells in gonads or in embryonic Mature teratoma, Immature teratoma,
rests dermoid cyst teratocarcinoma
4) To gain an overview of cancer epidemiology.
a. Incidence - >500K deaths/yr in US, 700K curable cancers/yr, Lung cancer biggest
killer in men and women, Prostate (men) and Breast (women) cancers are most
common, US, Lung cancer deaths US 2x> Japan,
Skin cancer New Zealand 6x> Iceland.
c. Environmental factors, drugs, chemicals
d. Hereditary tumors – inherited cancers, familial cancers, defective DNA repair.
e. Age – biggest risk factor
f. Acquired preneoplastic disorders – Predispositions: chronic atrophic gastritis =
gastric carcinoma, solar keratosis = skin cancer, leukoplakia = skin carcinoma.
g. Social factors – Smoking: Lung (90%), larynx (80%), esophagus (70%), and
bladder (30%). Sun exposure: skin whites (90%). Diet: animal fat colon cancer
(50%), Betal nut chewing: oral cancer India (90%).