chapter 5 neoplasia
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Chapter 5 Neoplasia. Background. - PowerPoint PPT PresentationTRANSCRIPT
Chapter 5 Neoplasia
Background
The tumor is a common disease all over the world. In
many countries especially developed countries, malignant
tumor has become the first or second leading cause of
death. Although many research works focused on
oncology and great progress has been made in
understanding tumors in the past decades, the morbidity
and mortality rate of malignant tumor is increasing. The
underlying causes include air pollution, pressure, excess
weight, unhealthy lifestyle, ageing population and so on.
ContentsDefinition
Structure Characteristics of Tumors
Nomenclature
Differentiation and Anaplasia
Growth, Local Invasion and Metastasis
Difference Between Benign and Malignant tumors
Effects of Tumors on the Hosts
Precancerous Lesions, Dysplasia, and Carcinoma in situ
Brief Introduction of Common Neoplasms
Definition of Neoplasm
A neoplasm is an abnormal mass of tissue, it’s
growth exceeds and is uncoordinated with that of the
normal tissue and persist in the same excessive manner
after cessation of the stimuli which evoke the change.
(Dr. RA Willis)
Definition of Neoplasm
At molecular level, neoplasm is disorder of growth
regulatory genes ( the activation of proto- oncogenes
and the inactivation of tumor suppressor genes ). It
develops in a multistep fashion, such that different
neoplasms, even of the same histological type, may
show different genetic changes.
Features of Neoplasm
1. Excessive cellular proliferation;
2. Lack of responsiveness to control mechanisms;
3. Lack of dependence on the continued presence of the
stimulus.
Structure Characteristics of Tumors
The gross appearance of tumor is varied. It is
usually related to histogenesis, site and biologic
behavior.
Structure Characteristics of Tumors
Gross appearance of tumor-shape:
a. polypoid
b. papillary
c. nodular
d. lobulated
e. cystic
f. fungating
g. ulcerated
Structure Characteristics of Tumors
lipoma
Hepatocellular carcinoma
Color of tumor:
Structure Characteristics of Tumors
Two basic components of all the tumors:
1. Parenchyma – the parenchyma is made up of proliferating neoplastic cells and largely determines the biologic behavior of the tumor. In addition, the classification, nomenclature and histological diagnosis are also made according to the parenchymal cells.
2. Supporting stroma – the supporting stroma is made up of connective tissue, blood vessels, and possibly lymphatics.
parenchyma
supporting stroma
Nomenclature
Basic principle:
Neoplasms are named according to binomial system
denoting their histogenic origin of the parenchymal
component and the biologic behavior.
NomenclatureBenign tumors: “ ~ oma”, e.g., fibroma; lipoma
Malignant tumors: “ ~ carcinoma, ~ sarcoma”
thyroid adenoma colonic adenoma
leiomyoma of uterus fibroadenoma of breast
heptocellular carcinoma
Squamous cell carcinoma adenocarcinoma of colon
osteosarcoma of bone
Differentiation and Anaplasia
Neoplasm differentiation denotes the degree to which a
neoplasm cell resembles the normal mature cells of the
tissue both morphologically and functionally.
What is neoplasm differentiation?
Differentiation and Anaplasia
Benign tumors are usually well differentiated. They
resemble closely their normal counterpart. Malignant
tumors, on the other hand, show variable degree of
differentiation. Malignant tumors that are composed of
undifferentiated cells are said to be “anaplastic”,that
means no morphological resemblance to normal tissue.
Differentiation and Anaplasia
lack of differentiation; literally means
‘to form backward,’ implying a ‘reverse differentiation’
of mature normal cells. For cancers, it does not represent
reverse differentiation. It means lack of differentiation .
What is anaplasia?
Growth, Local Invasion and Metastasis
The growth rate of neoplastic cells varies greatly
and is one of its chief factors that serves to
distinguish benign from malignant.
In a general rule, the degree of malignancy of a
neoplasm is correlated with its growth rate: the
more rapid the growth, the more malignant the
neoplasm.
Rate of growth and malignancy:
Growth, Local Invasion and Metastasis
Nearly all benign tumors grow as cohesive expansile
masses that remain localized to their site of origin.
a. Benign tumors grow slowly and usually develop a
fibrous capsule keeping the tumor as a discrete, readily
palpable and easily movable mass that can be excised.
b. When a benign tumor arises in a epithelial or mucosal
surface, the tumor grow away from the surface, often
forming a polypoid.
Invasion ( Infiltration)
LipomaHere is a benign lipoma on the serosal [si'rəusəl] surface of the small intestine. It has the characteristics of a benign neoplasm: it is well circumscribed, slow growing, and resembles the tissue of origin (fat).
Growth, Local Invasion and Metastasis
The growth of cancers, in contrast, is accompanied by
infiltration, invasion, and destruction of the
surrounding tissue.
a. In general, malignant tumors are lack of a well defined
cleavage plane and usually exhibit local invasiveness or
infiltration that make it difficult to be excised.
b. Malignant tumors on epithelial or mucosa surface may
form a protrusion in the early stages, but eventually
invade the underlying normal tissue.
Invasion ( Infiltration)
Squamous cell carcinoma of lung
Malignant neoplasms are also characterized by the tendency to invade surrounding tissues. Here, a lung cancer is seen to be spreading along the bronchi into the surrounding lung.
hepatic adenoma hepatocellular carcinoma
Here is a small hepatic adenoma that shows how well-demarcated an benign neoplasm is.
In contrast, this hepatocellular carcinoma is not as well circumscribed (note the infiltration of tumor off to the lower right) nor as uniform in consistency. It is also arising in a cirrhotic (nodular) liver.
Metastasis
Metastasis is to form a second neoplastic mass
through transfer of the neoplastic cells from the
first neoplasm to a distant site on separate from
the original tumor.
What is metastasis of neoplasms?
Metastasis
1. Lymphatogenous metastasis- The most common
pathway for initial dissemination of carcinomas, but
sarcomas may also use this route.
2. Hematogenous metastasis- This route is typical of
sarcomas but is also seen with carcinoma..
3. Metastasis in body cavities ( seeding )- Direct
seeding of body cavities or surface (exfoliation and
implantation on peritoneum, pleura, subarachnoid)
Routes of metastasis
characteristics Benign MalignantDifferentiation Well differentiated Range from well differentiate
to undifferentiated
Rate of growth Slow growth over a period of years
Rapid growth, sometimes erratic
Type of growth Expansile Progressive infiltration, invasion, and destruction of surrounding tissue
Separated from Yes, has fibrous capsule composed of stroma of native tissue
Poorly separated
Metastasis No Yes
Effect on host Often insignificant Significant, fever, anemia, infections, etc.
Recurrence Rare Often
Cell shape Monomorphic Pleomorphic Tumor giant cells
Nuclear chromatin
Normal Inreased, hyperchromatic; Peripheral clumping
Nucleoli Not prominent Prominent, irregular shape
Precancerous Lesions
A premalignant or precancerous lesion is an
abnormality in a tissue area which is a just a step
away from cancer.
a. Not all precancerous lesions change to cancer, but
most have potential to become malignant.
b. It is important to recognize precancerous lesions
because surgical excision is curative.
What is precancerous lesions?
Table 5-5 page114
Dysplasia
Dysplasia is an abnormality of both differentiation and
maturation.
This term should be restricted to abnormalities of cell
growth with the characteristics as following:
a. Increased size of the nucleus, (absolute and relative to the amount of cytoplasm)
b. Hyperchromatism
c. Abnormal chromatin distribution (coarse clumping)
d. Nuclear membrane is thickneng and wrinkling.
e. In squamous epithelium, mitotic figures appear in many layers.
What is dysplasia?
Carcinoma in situ
The term carcinoma in situ refers to an epithelial
neoplasm exhibiting all the malignant cellular
features. But it has not yet invaded with
through the epithelial basement membranes
separating it from potential route of metastasis.
It is only at this very early stage the excision of the tumor will guarantee a cure. So detection of carcinoma in situ is very important. In clinical practice, detection of carcinoma at the in situ stage, or detection of precancerous lesions is the aim of population screening programs for cervical, breast and some other carcinoma. Through these popular screening, many lives have been saved.
What is carcinoma in situ?