Chapter 5 Neoplasia

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Chapter 5 Neoplasia
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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.

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Contents

• Definition
• 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

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Definition of Neoplasm

• A neoplasm is an abnormal mass of tissue,
  its 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)

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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.

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Features of Neoplasm

• Excessive cellular proliferation
• Lack of responsiveness to control mechanisms
• Lack of dependence on the continued presence of
  the stimulus.

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Structure Characteristics of Tumors

• The gross appearance of tumor is varied. It is
• usually related to histogenesis, site and
  biologic
• behavior.

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Structure Characteristics of Tumors

• Gross appearance of tumor-shape
• polypoid
• papillary
• nodular
• lobulated
• cystic
• fungating
• ulcerated

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Structure Characteristics of Tumors
Color of tumor
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Structure Characteristics of Tumors

• Two basic components of all the tumors
• 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.
• Supporting stroma the supporting stroma is made
  up of connective tissue, blood vessels, and
  possibly lymphatics.

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Nomenclature

• Basic principle
• Neoplasms are named according to binomial system
  denoting their histogenic origin of the
  parenchymal component and the biologic behavior.

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Nomenclature

• Benign tumors oma, e.g., fibroma lipoma
• Malignant tumors carcinoma, sarcoma

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Differentiation and Anaplasia
What is neoplasm differentiation?

• Neoplasm differentiation denotes the degree
  to which a neoplasm cell resembles the normal
  mature cells of the tissue both morphologically
  and functionally.

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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.

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Differentiation and Anaplasia
What is 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 .

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Growth, Local Invasion and Metastasis
Rate of growth and malignancy

• 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.

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Growth, Local Invasion and Metastasis
Invasion ( Infiltration)

• Nearly all benign tumors grow as cohesive
  expansile masses that remain localized to their
  site of origin.
• 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.
• When a benign tumor arises in a epithelial or
  mucosal surface, the tumor grow away from the
  surface, often forming a polypoid.

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Lipoma Here is a benign lipoma on the serosal
si'r?us?l 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).
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Growth, Local Invasion and Metastasis
Invasion ( Infiltration)

• The growth of cancers, in contrast, is
  accompanied by infiltration, invasion, and
  destruction of the surrounding tissue.
• 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.
• Malignant tumors on epithelial or mucosa surface
  may form a protrusion in the early stages, but
  eventually invade the underlying normal tissue.

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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.
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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.
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Metastasis
What is metastasis of neoplasms?

• 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.

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Metastasis
Routes of metastasis

• Lymphatogenous metastasis- The most common
  pathway for initial dissemination of carcinomas,
  but sarcomas may also use this route.
• Hematogenous metastasis- This route is typical of
  sarcomas but is also seen with carcinoma..
• Metastasis in body cavities ( seeding )- Direct
  seeding of body cavities or surface (exfoliation
  and implantation on peritoneum, pleura,
  subarachnoid)

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Precancerous Lesions
What is precancerous lesions?

• A premalignant or precancerous lesion is an
• abnormality in a tissue area which is a just a
  step
• away from cancer.
• Not all precancerous lesions change to cancer,
  but most have potential to become malignant.
• It is important to recognize precancerous lesions
  because surgical excision is curative.

Table 5-5 page114
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Dysplasia
What is 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
• Increased size of the nucleus, (absolute and
  relative to the amount of cytoplasm)
• Hyperchromatism
• Abnormal chromatin distribution (coarse clumping)
• Nuclear membrane is thickneng and wrinkling.
• In squamous epithelium, mitotic figures appear in
  many layers.

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Carcinoma in situ
What is 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.