This document discusses neoplasms and tumors. It defines a neoplasm as an abnormal mass of tissue with uncontrolled growth that persists after stimuli stops. Neoplasms arise from genetic alterations in tumor cells and their progeny, causing excessive proliferation. Tumors remain dependent on the host for nutrition and blood supply. Cancers refer to malignant tumors that can invade other structures and metastasize to distant sites, potentially causing death. Both benign and malignant tumors contain neoplastic cells and a supportive stroma of blood vessels, connective tissue, and immune cells.

2. Introduction
 Oncology - study of tumors or neoplasms.
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3. Neoplasm
 An abnormal mass of tissue
 The growth of neoplasms exceeds and is
uncoordinated compared to that of the
normal tissues
 The growth also persists in the same
excessive manner after cessation of the
stimuli which evoked the change
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4. Neoplasm Cont’d
 Neoplasms result from genetic alterations
that are passed down to the progeny of the
tumor cells allowing excessive and
unregulated proliferation that becomes
autonomous
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5. Neoplasm Cont’d
 Tumors are monoclonal-The entire
population of neoplastic cells within an
individual tumor arises from a single cell
that has incurred genetic change
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6. Neoplasm Cont’d
 Tumors generally remain dependent on the
host for their nutrition and blood supply
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7. Cancer
 Refers to a malignant tumor
 Malignant-the lesion can invade and
destroy adjacent structures and spread to
distant sites (metastasize) to cause death.
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8. Basic Components of Tumors
 Clonal neoplastic cells that constitute their
parenchyma
 Reactive stroma -made up of :
 blood vessels
 connective tissue, and
 variable numbers of macrophages and
lymphocytes.
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9. Blood supply
 Tumor cells require an adequate stromal
blood supply to live and divide,
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10. Connective tissue
 The stromal connective tissue provides the
structural framework essential for the
growing cells.
 In some tumors, the stromal support is
scant hence the neoplasm is soft and
fleshy.
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11. Connective tissue Cont’d
 In other cases the parenchymal cells
stimulate the formation of an abundant
collagenous stroma(desmoplasia)hence
the tumor may be stony hard/scirrhous
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12. Nomenclature of Tumors
 Benign nomenclature
 Malignant nomenclature
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13. Benign Tumors Nomenclature
 Benign tumors of mesenchymal origin are
designated by attaching the suffix -oma to
the cell of origin e.g.
 Fibroma – fibrours tissue tumor
 Chondroma-cartilaginous tumor
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14. Benign Nomenclature cont’d
 Benign tumors of epithelial origin are
classified based on:
 cells of origin,
 microscopic pattern,
 macroscopic architecture.
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15. Benign Epithelial Neoplasms
 Adenoma - a benign epithelial neoplasm
derived from glands,
 Papilloma-Benign epithelial neoplasms
producing microscopically or
macroscopically visible finger-like or warty
projections from epithelial surfaces
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16. Benign Epithelial Neoplasms
 Cystadenomas-benign tumors that form
large cystic masses
 Papillary cystadenomas-tumors that
produce papillary patterns that protrude
into cystic spaces
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17. Malignant Tumors
Nomenclature
 Sarcomas- Malignant tumors arising in
mesenchymal tissue ; they have little
connective tissue stroma and so are fleshy
(e.g., fibrosarcoma, chondrosarcoma).
 Carcinomas- Malignant neoplasms of
epithelial cell origin derived from any of the
three germ layers
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18.  Lymphatic tissue-lymphomas
 CNS-glioma
 Bone marrow-leukemias
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19. Carcinomas
 Squamous cell carcinoma- a cancer in
which the tumor cells resemble stratified
squamous epithelium,
 Adenocarcinoma –a lesion in which the
neoplastic epithelial cells grow in glandular
patterns.
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20. Carcinomas Cont’d
 Sometimes the tissue or organ of origin
can be identified e.g.
 Renal cell adenocarcinoma
 Bronchogenic squamous cell carcinoma.
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21. Teratoma
 A tumor which contains recognizable
mature or immature cells or tissues
representative of more than one germ cell
layer and sometimes all three.
 May be:
 Benign(mature)-all the component parts
are well differentiated or
 malignant(immature)-components are
less well differentiated
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22. A Polyp
 A neoplasm, benign or malignant that
produces a macroscopically visible
projection above a mucosal surface and
projects into the lumen
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24. Differentiation and Anaplasia
 Differentiation- extent to which neoplastic
parenchymal cells resemble the
corresponding normal parenchymal cells,
both morphologically and functionally
 Anaplasia-Lack of differentiation
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25. Differentiation Cont’d
 In general:
 Benign tumors are well differentiated
 Anaplasia, is considered a hallmark of
malignancy.
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26. Rate of Growth
 Most malignant tumors grow more rapidly
than do benign tumors
 Rate of growth is dependent on:
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27. Rate of Growth Cont’d
 The doubling time of tumor cells
 The fraction of tumor cells that are in the
replicative pool (growth fraction)
 The rate at which cells are shed or die
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28. Doubling Time
 Tumor cells can be triggered to cycle
without the usual restraints due to
derangement of cell cycle controls
 However, total cell cycle time for many
tumors is equal to or longer than that of
corresponding normal cells.
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29. Proliferative Pool
 During the early phase of tumor growth,
the vast majority of transformed cells are in
the proliferative pool
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30. Proliferative pool Cont’d
 As tumors continue to grow, cells leave
the proliferative pool in ever-increasing
numbers hence by the time a tumor is
clinically detectable, most cells are not in
the replicative pool.
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31. Proliferative Pool
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32. Rate of Shed
 The rate of growth and progression of a
tumor is determined by an excess of cell
production over cell loss.
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33. Limitless proliferative capacity
 Cancers cells contain “stem- like”
properties- have limitless proliferative
capacity
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34.  Cancer stem cells could arise from normal
tissue stem cells or from more
differentiated cells that, as part of the
transformation process, acquire the
property of self-renewal.
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35. Local Invasion
 Nearly all benign tumors grow as cohesive
expansile masses that remain localized to
their site of origin- Encapsulation occurs
keeping the benign neoplasm as a
discrete, readily palpable, and easily
movable mass.
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36. Local Invasion Cont‘d
 Malignant tumors are accompanied by
progressive infiltration, invasion, and
destruction of the surrounding tissue.
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37. Local invasion Cont’d
 Hence
 They are poorly demarcated from the
surrounding normal tissue, and
 lack a well-defined cleavage plane.
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38. Benign Malignant
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39. Metastasis
 Metastases are tumor implants
discontinuous with the primary tumor.
 Metastasis unequivocally marks a tumor
as malignant
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40. Metastasis Cont’d
 The invasiveness of cancers provides them
with an opportunity for spread by permitting
them to penetrate into Body cavities, blood
vessels and/or the lymphatics.
 Occurs through:
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41. Direct seeding
 Seeding may occur whenever a malignant
neoplasm penetrates into a cavity
 Most often involved is the peritoneal cavity
though any other cavity may be affected.
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42. Lymphatic spread
 The most common pathway for the initial
dissemination of carcinomas and
sarcomas .
 The pattern of lymph node involvement
follows the natural routes of lymphatic
drainage.
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43. Hematogenous Spread
 Typical of sarcomas but is also seen with
carcinomas
 Involves veins more than arteries-veins
are more readily penetrated than are
arteries.
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44. Hematogenous Spread Cont’d
 Blood-borne cells follow the venous flow
draining the site of the neoplasm
 Tumor cells often come to rest in the first
capillary bed they encounter.
 Liver and lungs are most frequently
involved
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45. Liver Metastasis
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46. Characteristics Benign Malignant
Differentiation/anaplasia Well differentiated;
structure sometimes
typical of tissue of origin
Some lack of
differentiation with
anaplasia; structure often
atypical
Rate of growth Usually progressive and
slow; may come to a
standstill or regress;
mitotic figures rare and
normal
Erratic and may be slow to
rapid; mitotic figures may
be numerous and
abnormal
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47. Characteristics Benign Malignant
Local invasion Usually cohesive
expansile well-
demarcated masses that
do not invade or
infiltrate surrounding
normal tissues
Locally invasive,
infiltrating surrounding
tissue; sometimes may be
seemingly cohesive and
expansile
Metastasis Absent Frequently present; the
larger and more
undifferentiated the
primary tumor the more
likely are metastases
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