Benign and malignant neoplasms can be differentiated based on four features: differentiation and anaplasia, rate of growth, local invasion, and metastasis. Benign tumors are well differentiated, slow-growing, localized, and often encapsulated, while malignant tumors can be undifferentiated, fast-growing, invasive, and have a tendency to metastasize. The document discusses the characteristics of both types of tumors and provides details on mechanisms of metastasis.

1. DIFFERENCE BETWEEN BENIGN AND
MALIGNANT NEOPLASM

2. NEOPLASM:
 literally means new
growth.
 An abnormal tissue mass
that grows by cellular
proliferation more rapidly
than normal tissue mass ,
and continuous to grow after
the stimuli that initiated the
new growth cease
DEFINITION

3. NAMING
 BENINGN
Use cell type and suffix “ oma”
E.g. fibroma
 MALIGNANT
Use cell type and suffix
“sarcoma or carcinoma”

4. Ways to differentiate B/W BENIGN and
MALIGNANT NEOPLASM
 There are four different features by
which benign and malignant
neoplasms can be distinguished
 Differentiation and Anaplasia
 Rate of growth
 Local invasion
 Metastasis

5. Differentiation and ANAPLASIA
 Benign
Composed of well differentiated cell
e.g: lipoma, chondroma
Mitoses are rare and of normal
configuration.

6. MALIGNANT
 Range from well
differentiated to
completely
undifferentiated
 Adenocarcinomas is an
example of well
differentiated malignant
neoplasm.

7. ANAPLASIA
Malignant neoplasms that are
composed of undifferentiated
cells are said to be
anaplastic.

8. FEATURES OF ANAPLASTIC CELLS
 Show pleomorphism ( variation in size
and shape)
 Nuclei are hyper chromatic ( dark
staining)
 Increase nuclear to cytoplasmic ratio
1:1 ( 1:4 or 1:6 normal)
 Giant cells ( considerably larger than
normal cells)
 Mitoses are numerous

10. DYSPLASIA
 Disorderly but non-
neoplastic
proliferation is
called dysplasia...
 Also called pre
malignant

12. Features of DYSPLASTIC cell
 They show pleomorphism
 Nuclei are hyperchromatic
 Mitoses abundant than normal figures
 But not synonymous with cancer
because mild to moderate dysplasia
could be regressed if inciting causes
are removed.

13. EXCEPTIONS
 Some malignant tumours grow
slowly
 E.g.: Acute childhood
“leukaemia” initiate during
foetal development yet
manifest full blown cancer years
later

14. LOCAL INVASION
Benign
 Remain localized
don’t have
capacity to
infiltrate, invade
or metastasize
 They have capsule
(fibrous) that
separates them
from host tissues

15. Rate of growth
BENIGN
 Most benign tumours grow
slowly
 They are non-invasive
 They don’t cause metastasis
MALIGNANT
 They grow fast
 They are invasive
 They cause metastasis
 *Rate of growth correlates
inversely with level of
differentiation...poorly
differentiated tumours grow more
rapidly*

16. NOTE
 Lack of capsule does not always mean ,
tumour is malignant. Some benign
tumours lack capsule
 E.g. Benign vascular neoplasm of dermis

17. Malignant Neoplasm
 Malignant neoplasms invade surrounding
tissues
 They don’t have well defined capsule

18. CUT SECTION OF INVASIVE DUCTAL
CARCINOMA OF BREAST

19. Metastasis
 “Spread of cancer from one part of
the body to other”
 Metastases are secondary implants
of tumours that are discontinuous
with the primary tumours and
located in remote tissues

20. Tendency to METASTASIZE
 Not all cancers have equal tendency to metastasize
 E.g. Basal cell carcinomas of skin highly invasive
locally But rarely metastasize .
 while
 Osteogenic ( bones) sarcoma metastasize to lungs
at time of initial discovery

21. Ways of dissemination of
malignant tumours
 There are 3 pathways of dissemination
 1: seeding within the body
 2: Lymphatic spread
 3: Haematogenous spread

22. Seeding within the body
 Spread by seeding occurs when
neoplasm invade a natural body
cavity e.g.: Cancers of ovary

23. Lymphatic spread
 Primary tumour reaches at the
site of metastasis , where
secondary tumour is to be
formed by using lymphatic
system
 Most common in carcinomas (
malignant tumour of epithelial
origin)

24. SKIP METASTASES
 In some cases the cancer cells
seem to traverse the
lymphatic channels from
primary nodes to be trapped
in subsequent lymph nodes
producing so called skip
metastases.

25. Haematogenous spread
 Primary tumour reaches at the site of metastasis
where secondary tumour is to be formed by using
Blood circulatory system
 This spread is favoured by sarcomas ( malignant
cancer of parenchymal origin)
 Liver and lungs are most frequently involved in
secondary site of haematogenous dissemination .

26. A LIVER STUDDED
WITH METASTATIC
CANCER

27. Summary
 Benign and malignant tumours can be distinguished from one
another based on the degree of differentiation , rate of growth,
local invasiveness, and distant spread
 Benign tumours resemble the tissue of origin and are well
differentiated; malignant tumours are poorly or completely
undifferentiated(anaplastic).
 Benign tumours are slow growing ; Malignant tumours generally
grow faster
 Benign tumours have capsule; Malignant tumours don't have
capsule .
 Benign tumours remain localized to the site of origin ; Malignant
tumours are locally invasive and metastasize to distant sites.