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Subependymoma

KEY FACTS

TERMINOLOGY

• Rare, benign, well-differentiated, intraventricular

ependymal tumor, typically attached to ventricular wall

IMAGING

• Intraventricular, inferior 4th ventricle typical (60%)

• Other locations: Lateral > 3rd ventricle > spinal cord

• T2/FLAIR hyperintense intraventricular mass

○ Heterogeneity related to cystic changes; blood products

or Ca++ may be seen in larger lesions

• Variable enhancement, typically none to mild

• T2WI and FLAIR are often most sensitive sequences

TOP DIFFERENTIAL DIAGNOSES

• Ependymoma

• Central neurocytoma

• Subependymal giant cell astrocytoma

• Choroid plexus papilloma

• Hemangioblastoma

• Metastases

PATHOLOGY

• WHO grade I

CLINICAL ISSUES

• 40% become symptomatic, often supratentorial

○ Related to increased intracranial pressure,

hydrocephalus

• Present in middle-aged/elderly adults (typically 5th-6th

decades)

• Treatment: Conservative management with serial imaging

if asymptomatic patient

• Surgical resection is curative in most cases

• Excellent prognosis for supratentorial lesions

○ Recurrence is extremely rare

DIAGNOSTIC CHECKLIST

• If 4th or lateral ventricular hyperintense mass in elderly

man, think subependymoma

(Left) Sagittal graphic shows a

solid, well-circumscribed mass

arising from the floor of the

4th ventricle with mild mass

effect ﬈. Note the lack of

hydrocephalus, typical of

subependymoma. (Right)

Sagittal FLAIR MR shows a

solid, hyperintense mass along

the inferior 4th ventricle ﬈ in

a 64-year-old man with

headaches. Subependymoma

was found at resection. These

4th ventricular tumors are

often asymptomatic. T2 and

FLAIR are typically the most

sensitive sequences to identify

this WHO grade I tumor.

(Left) Axial T2WI MR shows a

hyperintense mass ﬈ along

the inferior 4th ventricle at

the level of the medulla

(classic imaging of a

subependymoma). (Right)

Axial T1 C+ MR shows an

enhancing mass in the 4th

ventricular outflow tract ﬈.

The moderate enhancement is

uncommon. Subependymomas

classically have no or minimal

enhancement. They can

protrude through the foramen

of Magendie. In this case,

tumor is also present anterior

to the cerebellar hemisphere

﬊ through the foramen of

Luschka.

Cysts, and Disorders

Brain: Pathology-Based Diagnoses: Neoplasms,

137