Page 635 - Concise Pathology for Exam Preparation ( PDFDrive )

620 SECTION II Diseases of Organ Systems

Neuronal tumours
(b)
(i)
Ganglioneuromas and gangliogliomas
Neuroblastomas
(ii)
Embryonal tumours
(c)
Medulloblastomas
(i)
Tumours of meningeal origin
(d)

(i) Meningiomas

(ii) Melanomas

(iii) Sarcomas
2. Secondary Tumours
3. Miscellaneous Tumours or Tumour-like Conditions
Cysts of developmental origin
(a)
Craniopharyngiomas
(b)
(c)
Chordomas
Dermoid cysts
(d)
Gliomas
Grading
1.
Three-tier system
�

(a)
Well-differentiated astrocytoma
(b)
Anaplastic astrocytoma
Glioblastoma
(c)
Four-tier system
2.

�
(a)
Grades I–IV based on nuclear pleomorphism, mitoses, endothelial proliferation
and necrosis (WHO grading)

a
s
)

(

b

Tumour grade expressed X/IV, eg, Grade II/IV for well-differentiated diffuse
fibrillary astrocytomas, Grade III/IV for anaplastic astrocytomas and Grade IV/IV

for glioblastomas.
Types
Astrocytomas: Gliomas derived from astrocytes are labelled astrocytomas. They are
1.
�
classified into the following subtypes:
(a) Diffuse astrocytomas

(i) Constitute 80% of all primary brain tumours.
(ii) Arise mainly from cerebral hemispheres.
(iii) Affected age is 40–60 years.
(iv) They show a spectrum of histological features depending on the predominant
cell type (fibrillary, protoplasmic, gemistocytic, etc.)
(v) Depending on the clinical course and outcome, they are classified into diffuse
well-differentiated astrocytomas (WHO Grade II/IV), anaplastic astrocytomas
(WHO Grade III/IV) and glioblastomas (WHO Grade IV/IV).

(b) �Anaplastic astrocytomas are tumours which show cellular pleomorphism, in-

creased proliferation of blood vessels, necrosis and numerous mitoses.
or
(c) �Glioblastoma multiforme GM (WHO Grade IV/IV tumours) have the follow-

ing salient features:
(i) They are the commonest gliomas in adults; usually seen in 3rd to 5th decades.
(ii) Cerebrum is the most frequent location. Also involve septum pellucidum, basal
ganglia, hypothalamus and corpus callosum (butterfly tumours).
(iii) May be of two types:
• De novo glioblastoma:

• Associated with amplification f EGFR gene, MDM2 overexpression, P16

o

deletion and TEN mutation

• Affects older patients
• Has a short history (arises de novo; not from low-grade astrocytomas)
• Secondary glioblastoma:
• Molecular genetics
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