Neoplasia literally means "new growth."
A neoplasm is defined as "an abnormal mass of
tissue the growth of which exceeds and is
uncoordinated with that of the normal tissues and
persists in the same excessive manner after the
cessation of the stimuli which evoked the change."
Fundamental to the origin of all neoplasms are
heritable (genetic) changes that allow excessive
and unregulated proliferation that is independent
of physiologic growth-regulatory stimuli.
neoplasm - a tumor, and the study of
tumors is called oncology (from oncos,
"tumor," and logos, "study of").
is divided into two types
Microscopic and gross characteristics are
considered to be relatively innocent.
It will remain localized.
Cannot spread to other sites.
Curable by local surgical removal.
Patient generally survives.
The lesion can invade and destroy adjacent
Cells are poorly differentiated.
Spread to distant sites (metastasize) to
Prognosis is very poor .
All tumors, benign and malignant, have two basic
The parenchyma, made up of transformed or
neoplastic cells – determines the biologic
The non-neoplastic stroma is made up of
connective tissue, blood vessels, and host-derived
general, benign tumors are designated by
attaching the suffix - oma to the cell type
from which the tumor arises.
tissue - fibroma
Cartilaginous tissue - chondroma
Adenoma is applied to benign epithelial neoplasms
producing gland patterns .
Papilloma are benign epithelial neoplasms, growing
on any surface, that produce microscopic or
macroscopic finger-like projections.
A polyp is an abnormal growth of tissue projecting
from a mucous membrane.
Cystadenoma are hollow cystic masses; typically
seen in the ovary.
Malignant neoplasms arising in mesenchymal tissue or its
derivatives are called sarcomas.
A cancer of fibrous tissue origin is a fibrosarcoma,
Composed of chondrocytes is a chondrosarcoma.
Malignant neoplasms of epithelial cell origin are called carcinoma.
Carcinomas that grow in a glandular pattern are called
adenocarcinomas, and those that produce squamous cells are
called squamous cell carcinomas.
of the neoplasms are of monoclonal
some instances, however, the tumor cells
may undergo divergent differentiation,
creating so-called mixed tumors.
of the female breast is an
example of common mixed tumor.
This benign tumor contains a mixture of
proliferated ductal elements (adenoma)
embedded in a loose fibrous tissue (fibroma)
A Teratoma is an encapsulated tumor with tissue
or organ components resembling normal derivatives
of more than one germ layer.
Usually, however, a teratoma will contain no organs
but rather one or more tissues normally found in
organs such as the brain, thyroid, liver, and lung.
A mature teratoma is typically benign and found
more commonly in women, while an immature
teratoma is typically malignant and is more often
found in men.
CHARACTERISTICS OF BENIGN AND MALIGNANT
Differentiation and anaplasia,
Rate of growth
Differentiation and Anaplasia
Benign neoplasms are composed of welldifferentiated cells that closely resemble their
normal counterparts. Eg.
- A lipoma is made up of mature fat cells laden
with cytoplasmic lipid vacuoles.
In well-differentiated benign tumors, mitoses are
extremely scant in number and are of normal
Malignant neoplasms are characterized by a wide
range of parenchymal cell differentiation, from
well differentiated to completely
Eg. well-differentiated adenocarcinomas of the
thyroid may contain normal-appearing follicles.
Between the two extremes lie tumors loosely
referred to as moderately differentiated.
Malignant neoplasms that are composed of
undifferentiated cells are said to be anaplastic.
Lack of differentiation, or anaplasia, is
considered a hallmark of malignancy.
It implies dedifferentiation, or loss of the
structural and functional differentiation of normal
Characteristics of Anaplastic cells –
Pleomorphism (i.e., marked variation in size and shape).
Nuclei are extremely hyperchromatic (darkly stained) and
The nuclear-to-cytoplasmic ratio may approach 1 : 1 instead of
the normal 1 : 4 or 1 : 6.
Giant cells that are considerably larger than their neighbors may
be formed and possess either one enormous nucleus or several
Anaplastic nuclei are variable and bizarre in size and shape.
6.The chromatin is coarse and clumped, and
nucleoli may be large.
7. Mitoses are often numerous and distinctly
atypical; sometimes appear as tripolar or
quadripolar forms .
8. Loss of normal polarity.
A term used to describe disorderly but non-neoplastic
Dysplasia is encountered principally in the epithelia.
It is a loss in the uniformity of individual cells and in their
Dysplastic cells exhibit considerable pleomorphism and often
possess hyperchromatic nuclei that are abnormally large for the
size of the cell.
Mitotic figures are more abundant than usual. Frequently the
mitoses appear in abnormal locations within the epithelium.
involve the entire
thickness of the
lesion is referred
to as carcinoma in
situ, a pre-invasive
stage of cancer
Dysplasia do not
Rate of Growth
Most benign tumors grow slowly.
Other influences, such as adequacy of blood
supply or pressure constraints, also may affect
the growth rate of benign tumors.
Adenomas of the pituitary gland locked into the
sella turcica have been observed to shrink
suddenly - necrosis - as progressive enlargement
compresses their blood supply.
rate of growth of malignant tumors
correlates in general with their level of
differentiation. Poorly differentiated – rapid
A benign neoplasm remains localized at its site of
It does not have the capacity to infiltrate, invade,
or metastasize to distant sites.
For example, as fibromas and adenomas slowly
expand, most develop an enclosing fibrous
capsule that separates them from the host tissue
However, not all benign neoplasms are encapsulated.
For example, the leiomyoma of the uterus
grow by progressive infiltration,
invasion, destruction, and penetration of
the surrounding tissue .
They do not develop well-defined
Metastasis is the development of secondary
implants (metastases) discontinuous with the
primary tumor, in remote tissues.
The properties of invasiveness and, even more so,
metastasis, - is the most confirmed characteristic
of a malignant tumor .
Route of metastasis
Malignant neoplasms disseminate by one of three
Seeding within body cavities,
spread is more typical of
carcinomas, whereas hematogenous
spread is favored by sarcomas.
Carcinoma of the breast usually arises in the
upper outer quadrant and first spreads to the
sentinal lymph node
A "sentinal lymph node" is defined as the first
lymph node in a regional lymphatic basin that
receives lymph flow from a primary tumor.
It can be delineated by injection of blue dyes or
Biopsy of sentinal lymph nodes allows determination
of the extent of spread of tumor, and can be used to
spread is the most feared
consequence of a cancer.
Since all portal area drainage flows to the
liver, and all caval blood flows to the
lungs, the liver and lungs are the most
frequently involved secondary sites in
Distinction between Benign and Malignant tumors:
The degree of differentiation,
Rate of growth,
Benign tumors resemble the tissue of origin and
are well differentiated; malignant tumors are poorly
or completely undifferentiated (anaplastic).
6. Benign tumors are slow growing, whereas malignant
tumors generally grow faster.