Pineocytoma

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

Overview

Pineocytoma (also known as a pinealocytoma) is a benign, slowly growing pineal parenchymal tumor.

Pathophysiology

• On gross pathology, pineocytoma is characterized by solid, sometimes with focal areas of cystic change, well-circumscribed mass with or without hemorrhage.
• On microscopic histopathological analysis, pineocytoma is characterized by:

• Cytologically benign cells (uniform size of nuclei, regular nuclear membrane, light chromatin)
• Pineocytomatous/neurocytic rosette, which is an irregular circular/flower-like arrangement of cells with a large meshwork of fibers (neuropil) at the centre

• According to the WHO classification of tumors of the central nervous system, pineocytoma is classified into a WHO grade I tumor.

Gallery

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  _{Intermediate magnification micrograph of a pineocytoma. HPS stain.}

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  _{High magnification micrograph of a pineocytoma. HPS stain.}

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  _{Very high magnification micrograph of a pineocytoma. HPS stain.}

Differentiating Pineocytoma from other Diseases

• Pineocytoma must be differentiated from:

• Pineal parenchymal tumor with intermediate differentiation
• Papillary tumor of the pineal region
• Pineoblastoma
• 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

Epidemiology

• Pineocytoma is a rare disease that tends to affect all the age groups, most commonly in the second decade of life.
• Pineocytoma affects men and women equally.

Prognosis

Prognosis is generally excellent, and the 5-year survival rate of patients with pineocytoma is approximately 86%.

Symptoms

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

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

Physical Examination

• Compression of the superior colliculi can also lead to a characteristic gaze palsy, known as Parinaud syndrome.
• Common physical examination findings of pineocytoma 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

Neurological

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

CT

• Head CT scan may be diagnostic of pineocytoma.
• Findings on CT scan suggestive of pineocytoma include a mass of intermediate density similar to the adjacent brain with peripheral calcifications.

MRI

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

MRI component	Findings
T1	Isointense to brain parenchyma
T2	Solid components are isointense to brain parenchyma Areas of cystic change Sometimes the majority of the tumor is cystic
T1 with gadolinium contrast	Solid components vividly enhance

References

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