Intrapineal glial-lined cyst, nonneoplastic

May form or involute over time

Majority 5-10 mm and asymptomatic; may be > 20 mm

Rarely hemorrhage, acute hydrocephalus, or Parinaud syndrome

Incidence of cysts > 5 mm: 11-20 years (3%), 21-30 years (3.4%), 70 years (< 0.5%)

If > 1 cm, nodularity, or associated clinical symptoms, recommend short interval follow-up

Well-defined, uni-/multiloculated cyst

Posterior to 3rd ventricle, above tectum, below internal cerebral veins

If large, may flattening of tectum, aqueduct compression, internal cerebral vein elevation

T1 and T2WI; Iso- to hyperintense to CSF

FLAIR: Usually hyperintense to CSF

DWI: Typically isointense to CSF

T2* GRE: Occasionally bloom if recent or old hemorrhage

± thin (< 2 mm) rim of enhancement = compressed pineal tissue

Rarely nodular enhancement

Avoid delayed post-contrast imaging; may show enhancement of cyst contents, making differentiation from tumors impossible

Tumor of primordial germ cells

Most common pineal tumor in children

30-40% of CNS germinomas in pineal region (50-60% suprasellar, up to 14% thalamus and basal ganglia)

Males > > females in pineal region

Males ≈ females in suprasellar region

Present with headache, hydrocephalus, and Parinaud syndrome (paralysis of upward gaze)

Classic well-defined mass “engulfs” pineal gland

CT: Iso-/hyperdense to gray matter

T1 and T2WI: Iso- to hypointense relative to GM

± hyperintense cysts T2WI

FLAIR: Iso- to hypointense relative to gray matter

DWI: Restricted diffusion

Avid contrast enhancement; “speckled” enhancement common

Relatively small lesion may ventricular obstruction

May engulf or displace pineal Ca++

MRS: ↑ choline, ↓ NAA, ± lactate

± enhancing subarachnoid metastases

2nd most common pineal tumor in children

Benign, nongerminomatous germ cell tumor

Mature, immature, and malignant types

Males > > females pineal and suprasellar region

Present with headache, hydrocephalus, and Parinaud syndrome (paralysis of upward gaze)

Heterogeneous pineal region mass with fat, soft tissue, Ca++, and cysts

T1WI: ↑ signal from fat, variable signal from Ca++

T2WI: Soft tissue iso- to hyperintense

FLAIR: ↓ signal intensity from cysts, ↑ signal intensity from solid tissue

MRS: ↑ lipid moieties on short echo

Fat suppression MR helps to confirm fat content

Difficult to distinguish mature from immature by imaging

Primitive neuroectodermal tumor (PNET) of pineal gland

Highly malignant

Children > adults

Up to 40% in infants

Large (usually > 3 cm) pineal mass

Hydrocephalus 2° aqueductal obstruction

“Exploded” peripheral Ca++ on CT

Extension into 3rd ventricle, thalamus, midbrain, cerebellar vermis common

CT: Solid portion hyperdense

T1WI: Solid portion iso- to hyperintense relative to GM

T2WI: Solid portion iso- to hyperintense relative to GM; mild peritumoral edema common; frequent necrosis; occasional hemorrhage

Moderate heterogeneous enhancement

MRS: ↑ choline, ↓ NAA

CSF spread in up to 40% at time of presentation