This document discusses various papillary tumors of the central nervous system. It begins by outlining the typical age ranges and locations for different tumor types, then describes key histological features. Several specific tumor types are discussed in more detail, including choroid plexus tumors, ependymomas, astroblastoma, meningioma, glioblastoma, craniopharyngioma, germ cell tumors, and metastatic tumors. Immunohistochemistry staining patterns are also provided to aid in diagnosis. The summary emphasizes that the diagnostic approach is to first consider the patient's age and radiology findings, examine histological features, and only use IHC when necessary to determine a tumor's primary origin.

1. Papillary Tumors of Central Nervous
System
PRESENTER:DR.ARGHA BARUAH
MODERATOR:DR.CSBR PRASAD

3. Approach:
1)Age
2)Location
3)Key Histological features

4. Age:
• Children: Choroid plexus papilloma,Choroid plexus carcinoma,ATRT, Yolk
sac tumor, Astroblastoma
• Young adults: Papillary ependymoma and myxopapillary ependymoma
• Middle age: Papillary meningioma, Papillary craniopharyngioma
• Old age: Metastasis to CNS
• Wide range:Papillary glioneuronal tumor

5. Location
• Ventricles: Choroid plexus papilloma and Choroid plexus carcinoma
• Spinal cord: Ependymoma
• Cerebral hemisphere: Astroblastoma,ATRT,Papillary glioneuronal
tumor,Metastasis
• Suprasellar: Craniopharyngioma,Yolk sac tumor
• Pineal: Papillary tumor of pineal gland,Yolk sac tumor

6. Key histopathological features:
• Pseudorosettes: Astroblastoma, Papillary meningioma, Ependymoma
• Rhabdoid cells: ATRT
• Nonkeratinizing squamous epithelium: Papillary Craniopharyngioma
• Schiller duval bodies and hyaline globules : Yolk sac tumor
• Myxoid: Myxopapillary ependymoma
• Cell are more spindle: Astroblastoma
• Cells have single layer of monomorphic cuboidal cells: Choroid plexus papilloma
• Cells are discohesive: Papillary meningioma

7. Choroid plexus tumors
Representing 2–4% of pediatric brain tumors
This group comprises of three entities:
• Choroid plexus papilloma (CPP; WHO grade I),
• Atypical CPP (WHO grade II),
• Choroid plexus carcinoma (CPC; WHO grade III).
Patients present with signs of hydrocephalus and raised intracranial
pressure

9. Choroid plexus carcinoma

10. • Immunohistochemically CPC express CK showing less frequent
positivity for S-100 and transthyretin.
• Mean Ki-67/MIB-1 labeling indices reported for CPP and CPC are 1.9%
and 13.8%, respectively.

11. Papillary ependymoma
• Papillary ependymoma is generally a slow growing tumor affecting children
and young adults, histologically corresponding to WHO grade II.
• It is most commonly seen in the fourth ventricle and spinal cord, followed
by the lateral ventricles and the third ventricle.
• Supratentorial ependymomas manifest with focal neurological deficits,
seizures, and features of intracranial hypertension
• Infratentorial ependymomas present with hydrocephalus and raised
intracranial hypertension.

12. Immunopositivity for S-100, vimentin, epithelial membrane antigen (EMA), and nestin is also seen.

13. Myxopapillary ependymoma
• Slow growing tumor manifesting in young adults typically involving the conus
medullaris, cauda equina, and filum terminale of the spinal cord and corresponds
to WHO grade I.
• The frequency of this tumor is 9-13% among all ependymomas.
• The mean age of 36 years has been reported with a male: female ratio of 2.2:1.
• It typically presents with back pain of long duration
• Prognosis is extremely favourable.

14. Immunohistochemistry for GFAP, S-100, and vimentin is positive.

15. Astroblastoma
• Rare glial neoplasm mainly affecting children, adolescents, and young
adults, typically involving the cerebral hemispheres.
• Due to the insufficient epidemiological and clinicopathologic data, this
tumor still awaits a WHO grade.
• Cytoplasmic immunopositivity for vimentin, S-100, and GFAP is
characteristic.
• Cytoplasmic immunopositivity for vimentin, S-100, and GFAP is
characteristic.

17. Papillary meningioma
• Rare tumors
• These are highly aggressive tumor corresponding to WHO grade III with a tendency to invade, recur, and
metastasize.
• Majority arise in intracranial (cerebral convexities), intraspinal (thoracic regions), or orbital locations.
• Middle aged patients, the female: male ratio is 1.7:1.
• Clinically, headache and seizures are the common presenting features.
• Diagnosis of papillary meningioma is considered only when this architectural pattern is exhibited in > 50% of
the tumor.
• Immunopositivity for EMA, vimentin, and S-100 is characteristic. Mean Ki-67/MIB-1 labeling indices reported
for papillary meningioma are generally > 20%.

19. Papillary glioneuronal tumor
• This neoplasm being extremely rare still lacks a population-based epidemiologic data.
• This tumor manifest over a wide range of ages (4–75 years); the mean age at presentation being
27 years.
• There is no gender bias.
• It corresponds to WHO grade I.
• It shows a predilection for the temporal lobes.
• Headache and seizures are the main clinical features
• Immunohistochemically, the glial cells are GFAP positive while the interpapillary cells are
synaptophysin,neuron specific enolase (NSE), and NeuN positive. MIB-1 labeling indices are in the
range of 1–2%.

21. Atypical teratoid/rhabdoid tumor
• Highly malignant CNS tumor (WHO grade IV), occurring most frequently in
infants, with most patients being aged less than 3 years
• Male: female ratio ranges from 1.6 to 2:1 showing a consistent male
predominance.
• ATRTs account for 1–2% of pediatric brain tumors and approximately 10%
of the infantile CNS tumors.
• This tumor may occur in either supratentorial or infratentorial location,
the ratio of supratentorial to infratentorial being 1.3:1.

23. • Rhabdoid cells are immunopositive for EMA, vimentin, and
smooth muscle actin (SMA).
• Expression of GFAP, neurofilament protein (NFP),
synaptophysin, and keratins are also common .
• Currently, INI1 is considered the most sensitive and specific
marker for ATRTs.
• Ki-67/MIB-1labeling indices reported for ATRTs are often > 50%,
focally up to 100%

24. Papillary Craniopharyngioma
• Papillary craniopharyngioma, the recently identified variant of craniopharyngioma, typically
affects the adults (mean age 40-55 years) involving the suprasellar region or the third ventricles.
• It is a benign tumor and corresponds histologically to WHO grade I.
• Craniopharyngiomas in general account for 1.2-4.6% of all intracranial tumors.
• Male and female are equally affected.
• Clinical features include visual loss,endocrine deficiencies, raised intracranial tension, diminished
mental acuity, and personality changes.
• MIB-1 immunopositivity is randomly distributed and are considerably higher than might be
expected considering the benign nature of the neoplasm.

26. Yolk Sac Tumor
• The incidence of this tumor varies geographically.
• All age groups affected but majority affect patients aged younger than 25
years.
• This tumor is more common in males.
• Midline location (third ventricle, pineal region) is the most common
followed by the suprasellar compartment.
• Clinical presentation varies according to the location.

27. • Periodic acid Schiff (PAS) positive/diastase resistant, variably sized,
cytoplasmic hyaline globules lying within the epithelial cells or
in the stroma. Mitosis is variable.
• Immunohistochemistry shows diagnostic cytoplasmic positivity for
alpha fetoprotein (AFP).

29. Papillary tumor of the pineal region
• Papillary tumor of the pineal region (PTPR) is a recently recognized
rare neuroepithelial tumor that occurs exclusively in the pineal
region, most often in adults.
• Incidence is not determined till date because of the rarity of this
neoplasm.
• Similarly histological grading criteria remain to be identified.PTPR has
been identified in both children and in adults (mean age 32 years).

31. • Immunohistochemistry shows strong positivity for keratins in the
papillary structures.
• PTPRs also show immunopositivity for vimentin, S-100, NSE,
microtubule associated protein 2 (MAP2), Neural cell adhesion
molecule(N-CAM), and transthyretin
• The Ki-67/ MIB-1 labeling indices reported for PTPRs are moderate
showing higher indices in tumors of young patients.

32. Metastatic Tumors of the CNS
• Metastatic tumors are the most common CNS neoplasms.
• The incidence of CNS metastases increases from < 1/100,000 below 25
years of age to > 30/100,000 at the age of 60 years.
• The most common sources of brain metastases in adults are, in descending
order, lung cancer, breast cancer, melanoma, renal cancer, and colon
cancer; in children, in descending order, leukemia, lymphoma,osteogenic
sarcoma, rhabdomyosarcoma, and Ewing sarcoma.
• The most common location for CNS metastases is the cerebral
hemispheres, followed by cerebellum.

33. • Immunohistochemical expression is variable.
• CNS metastases of the carcinomas usually show strong
immunopositivity for CK and EMA
• The Ki-67/MIB-1 labeling indices reported for metastatic tumors
of the CNS are markedly high

37. Summary
• Basic approach is first check the age
• Correlate with radiological findings especially for the location
• Check for key histological features
• Run IHC only when in doubt and to rule out primary origin of
metastatatic lesions.

38. References:
• Pant I, Chaturvedi S. Diagnostic approach to histopathology of central
nervous system papillary tumors. Astrocyte 2014;1:124-31
• Suki D. The epidemiology of brain metastases. In: Intracranial
metastases; Current management strategies. In: Sawaya R, editor.
Malden, MA, USA: Blackwell Futura Publishing; 2004.