1. NEOPLASIA
H.A. MWAKYOMA, MD

2. DEFINITIONS :
TUMOUR: - was originally applied to the swelling caused by inflammation
- the term is now equated with
neoplasm
ONCOLOGY:- (Geek “oncos” = Tumour, is the study of tumours or neoplasm)
NEOPLASM:- definition by British oncologist Sir Rupert Willis has come closest

3. DEFINITION OF NEOPLASM:
Is an abnormal mass of tissue
The growth of which exceeds and is uncoordinated with that of the normal tissue
The growth persists in the same excessive manner after cessation of the stimuli which evoked the change
Addition:- the abnormal mass is purposeless, preys on the host (Parasitic)

4. Additions to the definition of neoplasm cont--
The abnormal mass is virtually autonomous.
The neoplasm preys on the host in sofar as the growth of the neoplastic tissue competes with the normal cells and tissues for energy and nutritional
substrate

5. Additions to definition of neoplasm cont--
In as much as these masses my flourish in a patient;
The patients wastes away
The degree of autonomous of the neoplasm later is not complete
All neoplasms ultimately depend on the host for the nutrition and vascular blood supply and endocrine support.

6. TYPES OF NEOPLASMS There are 2 groups of neoplasms
The groups are divided according to their behavioural characteristics namely;
BENIGN NEOPLASMS and
MALIGNANT NEOPLASMS

7. BENIGN NEOPLASMS: Are the ones which remain localized
Do not invade the tissue in which they grow
Do not spread through the host body
Do not normally cause serious damage EXCEPT as a result of critical positioning or function

8. MALIGNANT NEOPLASMS: Invade and destroys the host tissue
Spreads throughout the body of the host
It is invariably fatal if unchecked by removal or treatment
CANCER:
Cancer and malignant are commonly used as synonymous of a malignant neoplasm,
Ie cancer is a common term for all malignant tumours. (cancer –Latin word for “Crab”)

9. NOMECLATURE AND CLASSIFICATION OF NEOPLASM
It is usual to classify neoplasms according to:-
The cell type from which they originate (HISTOGENESIS)
Epithelial or
Mesenchymal (connective) tissue

10. CLASSIFICATION OF NEOPLASM cont--
Biological behaviour:-
Whether they are benign or malignant
Names of individuals:-
Hodgkin’s disease – a malignant tumour of lymphnodes = Lymphoma, which has no malignant counterpart).

11. Names of individuals cont--
Burkitt’s lymphoma - a malignant neoplasm originating from B-cells
Grawitz tumour = Renal cell carcinoma (arising from renal tubular cells)

12. Classification of neoplasm cont--
Organs:-
Hepatoma – tumour of the liver parenchymal cells
- is a malignant version of Hepatocellular carcinoma
Tumours derived from 3 germ layers (Endo-Meso-Ectoderm)
Teratoma – derived from totipotential cells in gonadal or embryonal rests (may be benign or malignant)

13. NOT TRUE TUMOURS: HARMATOMA:
Are congenital anomalies due to abberant differentiation of cells that results in a mass of disorganized but mature specialized cells or tissue indigenous to the particular site.
Examples; islands of cartilage or bllood vessels within the lung.

14. Not true tumours cont--
CHORIOSTOMA:-
A normal ectopic piece of tissue in an organ that is not normally found at the site
Examples; - a piece of adrenal gland under the capsule of the kidney or
- a nodule of pancreatic tissue in the submucosal of the small intestine or stomach

15. COMPONENTS OF TUMOURS:
All tumours benign or malignant have 2 basic components;
Parenchyma – proliferating neoplastic cells and
Supportive stroma – made up of connective tissue, blood and lymphatic vessels

16. NOMECLATURE OF TUMOURS:
Naming of tumours is based on parenchyma component.
The SUFFIX“OMA” denotes benign neoplasm
Note that there is no rule without exception
E.g. Granuloma and Harmatoma are not neoplasms
- Heptoma, lymphoma, melanoma are malignant tumors
The tissue origin appears as a “PRIFIX”

17. BENIGN TUMORS: Benign mesenchymal tumours:-
Are those arising in muscle, bones, cartilage, fat, blood/lymphatic vessels, fibrous tissue, etc
Are classified histogenetically according to cell type

18. Benign tumours cont---
Benign epithelial tumours:-
Are classified on;
The basis of cells of origin(histogeneticaly)
Microscopic architecture
Macroscopic pattern
EXAMPLES:
ADENOMA:
Benign epithelial neoplasm that form glandular pattern or

19. ADENOMA cont--
Tumours derived from glands but not necessarily reproducing glandular pattern
(e.g. renal tubules, adrenal cortex cells)

20. PAPILLOMA:
Benign epithelial neoplasm producing microscopically or macroscopically finger-like or warty projection.

21. Squamous cell papilloma-skin

22. POLYP
Benign epithelial neoplasm which produces macroscopically visible projections above a mucosa surface and into the lumen. e.g. gastric or colonic

23. Colon adenomatous polyp

24. Colon polyp

25. Familial polyposis

26. HISTOGENETIC- cell of origin benign tumours
Fibrous
Fatty
Cartilage
Smooth muscle
Striated muscle
Bone
Meninges
Blood vessels
Fibroma
Lipoma
Chondroma
Leiomyoma
Rhabdomyoma
Osteoma
Meningioma
Angioma

27. Tissue of origin benign tumours
Stratified squamous epithelium
Basal cell
Transitional epithelium
Sweat gland
Liver cell
Sebaceous gland
Bile duct
Placenta epithelium (trophoblasts)
Squamous cell papilloma
Basal cell papilloma
Transitional cell papilloma
Sweat gland adenoma
Liver cell adenoma
Sebaceous gland adenoma
Bile duct adenoma
Hydatidform mole

28. Benign tumours -histogenesis
There are some tumours which are derived from more than one neoplastic cell type
These tumours are of 2 types:-
Mixed tumours:
Usually are derived from one germ layer
e.g. salivary glands (myoepithelial cells) – PLEOMORPHIC ADENOMA- mixed tumour of salivary gland

29. More than one neoplastic cells cont--
TERATOMA:
Are derived from more than one germ layer from totipotent cells in gonads (testes, ovary or embryonic rests)

30. MALIGNANT NEOPLASMS:
Malignant tumour nomeclature are essentially follows the same scheme used for benign neoplasm with certain additions.
Cancers arising in MESENCHYMAL tissue are called SARCOMAS (Greek “sark”-fleshy) because they usually have very little connective tissue stroma and so are fleshy.
Malignant neoplasms of EPITHELIAL origin, are derived from 3 germ layers and are called CARCINOMAS.

31. MALIGNANT NEOPLASMS cont--
TISSUE OF ORIGIN
Fibrous
Fatty
Cartilage
Bone
Smooth muscle
Streated muscle
Synovium
Blood vessels
TYPE OF TUMOUR
Fibrosarcoma
Liposarcoma
Chondrosarcoma
Osteosarcoma
Leiomyosarcoma
Rhabdomyosarcoma
Synoviosarcoma
Angiosarcoma

32. MALIGNANT NEOPLASMS cont-
TISSUE OF ORIGIN
Stratified squamous epithelium
Basal cell
Transitional epithelium
Glandular epithelium
Melanocyte
Placental epithelium
Liver cells (hepatocytes)
TYPE OF TUMOUR
Squamous cell carcinoma
Basal cell carcinoma
Transitional cell carcinoma
Adenocarcinoma
Melanoma
Choriocarcinoma
Hepatocellular carcinoma

33. BENIGN VS MALIGNANT TUMOURS
Differences between benign and malignant tumours:-
BASIC DIFFERENCES.
Degree of differentiation
Resemblance to normal “parent” tissue
Well differentiation
Moderately differentiated
Poorly differenciated or anaplastic (primitive cell types)

34. BASIC DIFFERENCES cont--
Note that tumours may be undergoing uncontrolled proliferention, but may still be able to differentiate into cell types that closely resemble their normal counterparts
Benign tumours are usually well differentiated
Malignant tumours may vary from well to poorly differentiated

35. BASIC DIFFERENCES cont--
Poorly differentiated tumours are usually “aggressive” (carry a poorer prognosis due to rapid growth, early metastasis and/or poor response to therapy)
Rate of tumour growth:
Most benign tumours grow slowly over a period of years
Most malignant tumours tend to grow rapidly over a period of months (from discovery) but also tend to grow erratically.

36. Rate of growth cont--
The rate of growth may depend on tissue type:- e.g. SARCOMA tend to grow rapidly than carcinomas
The rate of growth generally correlates degree of differentiation, with undifferentiated tumours tending to grow faster

37. Rate of growth cont--
Rarely both benign and malignant tumours may actually stop growing and reduce in size or disappear (the so-called “miracle” cure), e.g. very rarely malignant melanoma may regress and disappear
Hormones may influence the rate of growth of tumour e.g. leiomyoma of uterus (fibroid), may grow rapidly in pregnancy and disappear after menopause (oestrogen dependent)

38. BASIC DIFFERENCES cont--
Local invasion:
Generally benign tumours grow slowly by expansion and develop a fibrous capsule
Fibrous capsule usually allow easy surgical enucleation
Some benign tumours are not well encapsulated.

39. LOCAL INVASION: Malignant tumours are locally invasive,
They infiltrate the surrounding tissue and
Usually give irregular margins that are not encapsulated
Surgical removal requires a wide excision margin of “normal tissue to be resected (say, 2-3 cm) to ensure that all malignant cells are removed.

40. Local invasion cont--
Malignant tumours may “erode” into normal blood vessels, increasing the likehood of metastasis ((see later)

41. METASTASIS:
By definition, malignant tumours can metastasise, although their ability to do so varies greatly
Note that a tumour does not have to have metastasized before it is labled malignant

42. ABBERANT OR ABNORMAL FUNCTION
Is more likely to occur in malignant tumours e.g. the secretion of abnormal or excess quantities of hormones

43. MICROSCOPIC DIFFERENCES:
Organization of tumour cells:
polarity:- tumour cells are organized into structures resembling their tissue of origin;
e.g. glandular tumors often form glandular structures
The more regular and ordered these structures are, the less likely they are malignant

44. POLARITY cont--
Glands that are haphazard in size and organization suggest malignancy
Therefore there is LOSS OF POLARITY in malignant tumours unlike in benign ones. (lack of oriatation – disordered arrangement)

45. MICROSCOPIC DIFFERENCES cont--
Nuclear- cytoplasmic ratio (N:C ratio):
Unlike in benign tumours, the nuclei in malignant tumours are disproportionately larger for the cell.
The N:C ratio approach 1:1, instead the normal 1:4 or 1:6

46. Microscopic differences cont--
Variation in size and shape (Pleomorphism):
In malignant tumours, both cells and nuclei are variable in size and shape (Pleomorphic) and hapharzadly arranged, unlike in benign tumours.

47. Microscopic differences cont--
Staining of nuclei:
Characteristically, the nuclei contain abundance of DNA and extremely dark staining (Hyperchromatism) in malignant tumours rather than benign ones.

48. Microscopic diffrences cont--
Mitoses:
There is a large number of mitoses, often used as a parameter of the aggressiveness of cancer.
The presence of mitoses does not necessarily indicate that the tumour is malignant – MORE important are Atypical bizarre (ABNORMAL) mitotic figures.

49. MITOSES cont-- Benign tumours grow slowly with low mitotic rate.
Malignant tumours grow rapidly with high mitotic rate and abnormal mitoses