Pineocytoma

KEY FACTS

TERMINOLOGY

• Pineocytoma (PC), pineal parenchymal tumor (PPT)

• PCs are composed of small, uniform, mature cells

○ Cells resemble pineocytes

IMAGING

• General features: Circumscribed, enhancing pineal mass

○ May mimic benign pineal cyst or PPT of intermediate

differentiation (PPTID)

○ Typically < 3 cm

○ May compress adjacent structures

○ Rarely extends into 3rd ventricle, rarely invasive

○ Can compress aqueduct → hydrocephalus

• CT

○ Circumscribed iso-/hypodense pineal region mass

○ Peripheral ("exploded") Ca++ common

○ CECT: Enhances (solid, ring, nodular)

• MR (most sensitive)

○ Cystic change may be present

○ Enhancement may be solid or peripheral

TOP DIFFERENTIAL DIAGNOSES

• Nonneoplastic pineal cyst

• PPTID

• Pineoblastoma

• Germinoma, other germ cell tumors

CLINICAL ISSUES

• Headache, dorsal midbrain (Parinaud) syndrome most

common features

• Increased intracranial pressure, ataxia, hydrocephalus,

mental status changes may occur

• Most common in adults, mean 40 years

• Stable or slow-growing tumor

• Germ cell markers (α-fetoprotein, hCG) absent

• Surgical excision or stereotactic biopsy is primary treatment

○ Complete surgical resection generally curative

(Left) Sagittal graphic shows a

cystic pineal gland mass ﬈

with a fluid-fluid level and

nodular tumor along the

periphery of the mass, typical

of pineocytoma. No significant

mass effect is present.

Pituicytomas may be found

incidentally or present with

hydrocephalus. (Right) Axial

NECT shows a classic example

of a pineocytoma. Note the

"exploded" peripheral

calcification ſt in this small

mass that arises from the

pineal region. The tumor is just

over 1 cm in size. There is no

hydrocephalus.

(Left) Sagittal T1 MR of a 50-

year-old woman with

headache shows a cystic

pineal region mass ſt with

associated ventriculomegaly

st and local mass effect on

the tectum ﬊. Mass effect on

the superior tectum often

results in dorsal midbrain

(Parinaud) syndrome. (Right)

Axial FLAIR MR in the same

patient shows the

hyperintense, lobular pineal

region mass ſt with

associated ventriculomegaly.

Pineocytoma was diagnosed

at resection. These WHO

grade I tumors are often

stable for years.

Brain: Pathology-Based Diagnoses: Neoplasms,

Cysts, and Disorders

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