Pineoblastoma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Synonyms and keywords: Pineoblastomas; Pinealoblastoma; Pinealoblastomas; PB; Pineal parenchymal tumor; Pineal gland tumor; Brain tumor

Overview

Pineoblastoma is a rare, malignant pineal parenchymal tumor. It is a supratentorial midline primitive neuroectodermal tumor. It is considered as a WHO grade IV tumor according to the WHO classification of tumors of the central nervous system.

Pathophysiology

Pathogenesis

Pineoblastoma originates from the neuroectodermal cells. It is the least differentiated pineal gland tumors, with pineocytoma and pineal parenchymal tumour with intermediate differentiation representing better differentiated tumors along the same spectrum.

Associated Conditions

Pineoblastoma may occur in patients with hereditary uni- or bilateral retinoblastoma. When retinoblastoma patients present with pineoblastoma, this is characterized as "trilateral retinoblastoma".

Gross Pathology

On gross pathology, pineoblastoma is characterized by solid, large poorly defined masses.

Gallery

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  _{An autopsy specimen showing a rather large pineal tumor. It was a pineoblastoma composed of highly cellular sheets of anaplastic cells with irregular hyperchromatic nuclei and brisk mitotic activity – resembling medulloblastoma and retinoblastoma.}

Microscopic Pathology

On microscopic histopathological analysis, pineoblastoma is characterized by:

• Hypercellular
• Tightly packed small round blue cells (high nuclear to cytoplasmic ratio)
• Oval and angulated hyperchromatic nuclei with atypia
• Mitoses
• Homer-wright & Flexner-Winterstein rosettes
• Fleurettes

Gallery

• 

  _{Pathology specimen of a pineoblastoma (HE stain, x200 magnification).}

• 

  _{Paraffin sections show fragments of a densely hypercellular tumour. Tumour cells have small round, oval and angulated hyperchromatic nuclei and delicate processes which show strong immunostaining for neurofilament protein (NFP). Tumour cells are arranged in diffuse sheets. Prominent Homer-Wright rosettes are noted in several areas. Scattered mitotic figures are identified. No areas of necrosis are seen.}

Immunohistochemistry

Pineoblastoma is demonstrated by positivity to tumor markers such as:

• GFAP
• Neurofilament
• Synaptophysin
• MIB-1
• Ki-67

Gallery

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  _{Immunohistochemical stain of a pineoblastoma demonstrating positivity to neurofilament.}

• 

  _{Immunohistochemical stain of a pineoblastoma demonstrating positivity to GFAP.}

Differentiating Pineoblastoma from other Diseases

Pineoblastoma must be differentiated from:

• Pineocytoma
• Pineal parenchymal tumor with intermediate differentiation
• Papillary tumor of the pineal region
• Pineal germinoma
• Pineal embryonal carcinoma
• Pineal choriocarcinoma
• Pineal yolk sac carcinoma (endodermal sinus tumor)
• Pineal teratoma
• Pineal cyst
• Astrocytoma of the pineal gland
• Meningioma near pineal gland
• Pineal metastasis
• Cavernoma in pineal region
• Aneurysm in pineal region
• Glioblastoma multiforme
• Medulloblastoma

Epidemiology and Demographics

Prevalence

Pineoblastoma constitutes approximately 0.1% of the intracranial neoplasms.

Age

Pineoblastoma is a disease that tends to affect the children and young adult population.

Gender

Pineoblastoma affects men and women equally.

Natural History, Complications and Prognosis

Natural History

Pineoblastoma is the most agressive pineal parenchymal tumor. If left untreated, patients with pineoblastoma may progress to develop seizures, obstructive hydrocephalus, local recurrence, and CSF metastasis.

Complications

Common complications of pineoblastoma include:

• Obstructive hydrocephalus
• Local recurrence
• CSF metastasis

Prognosis

Prognosis is generally poor, and the 5-year survival rate of patients with pineoblastoma is approximately 58%.

History and Symptoms

History

When evaluating a patient for pineoblastoma, you should take a detailed history of the presenting symptom (onset, duration, and progression), other associated symptoms, and a thorough family and past medical history review.

Symptoms

• The clinical presentation of pineoblastoma is mainly from the obstructive hydrocephalus secondary to compression of the tectum of the midbrain and obstruction of the aqueduct.
• Symptoms of pineoblastoma include:

• Headaches
• Nausea
• Vomiting
• Seizures
• Tinnitus
• Hearing loss
• Sleepiness
• Irritability
• Personality changes
• Double vision
• Trouble coordinating motor movements
• Difficulty walking
• Slowed growth

Physical Examination

Compression of the superior colliculi can lead to a characteristic gaze palsy, known as Parinaud syndrome. Common physical examination findings of pineoblastoma include:

HEENT

• Bulging soft spots (fontanelles)
• Eyes that are constantly looking down (sunsetting sign)
• Deficiency in upward-gaze
• Pupillary light-near dissociation (pupils respond to near stimuli but not light)
• Convergence-retraction nystagmus
• Papilledema

Neurological

• Mental retardation
• Muscle spasms
• Loss of bladder control
• Ataxia
• Cranioneuropathies

• VI^th nerve palsy

CT

• Head CT scan may be diagnostic of pineoblastoma.
• Findings on CT scan suggestive of pineoblastoma include a mass with a solid component that tends to be slightly hyperdense compared to adjacent brain due to high cellularity. Calcification is present that is peripherally disperse or "exploded", similar to pineocytoma.

Gallery

• 

  _{Pineal calcification: exploded calcification of tumors of pineal cell origin, whereas engulfed calcification by germinomas.}

• 

  _{Single head CT image demonstrates a soft tissue mass in the region of the pineal gland with eccentric calcification (anterior) and evidence of hydrocephalus.}

MRI

• Brain MRI may be diagnostic of pineoblastoma.
• Features on MRI suggestive of pineoblastoma include:

MRI component	Findings
T1	Isointense to hypointense to adjacent brain
T2	Isointense to adjacent brain Areas of cyst formation or necrosis may be present
T1 with gadolinium contrast	Vivid heterogenous enhancement
Diffuse weighted imaging/Apparent diffusion coefficient	Restricted diffusion due to dense cellular packing ADC values are typically 400-800 mm2/s

Treatment

The predominant therapy for pineoblastoma is surgical resection. Adjunctive chemotherapy and radiation may be required.

References

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