C.N.S.Pineal Region Masses

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Pineal Region Massesa) Intrinsic Pineal Massb) Extrinsic Pineal Mass

The pineal gland is located in the midline at the level of the midbrain , it is situated between the thalami at the posterior aspect of the 3rd ventricle , the internal cerebral veins and vein of Galen are located superior & posterior to the pineal gland respectively

A-Genu of the Corpus CallosumB-Anterior Horn of the Lateral VentricleC-Internal CapsuleD-ThalamusE-Pineal GlandF-Choroid PlexusG-Straight Sinus

Normal Pineal gland

Normal pineal anatomy , sagittal T1 shows the normal anatomy of the pineal region , the pineal gland (arrow) lies below the splenium of the corpus callosum , the flow void from the vein of Galen crosses just above the pineal gland , the tectal plate is located immediately inferior to the gland

Axial view1-Pineal gland 2-Habenula3-3rd ventricle 4-Pulvinar5-Lateral ventricle

Axial View1-Posterior commissure2-3rd ventricle 3-Lateral ventricle4-Pineal gland

Coronal View1-Pineal gland2-Lateral ventricle 3-Corpus callosum 4-Fornix5-Thalamus6-Middle cerebellar peduncle

Sagittal View1-Posterior commissure2-Cerebral aqueduct (of Sylvius)3-Tectum4-Fourth ventricle5-Cerebellum6-Quadrigeminal cistern7-Pineal gland8-Splenium , corpus callosum9-Third ventricle

a) Intrinsic Pineal Mass :1-Benign Cyst2-Germ Cell Tumors3-Parenchymal Cell Tumors4-Metastases

1-Benign Cyst :a) Incidenceb) Radiographic Featuresc) Differential Diagnosis

a) Incidence :-Pineal cysts are typically found in young aged

adults (20-30 years of age) more in women-Simple cystic structure within the gland

measuring < 1.5 cm-Unlikely to be significant when no mass effect

and when there are no relevant symptoms

b) Radiographic Features :*CT :-Well circumscribed fluid density lesions with

thin rim calcification seen in 25%-Some peripheral enhancement is also often

seen-The internal cerebral veins are elevated and

splayed by the cyst

1-Posterior commissure2-Habenular commissure3-Internal cerebral vein4-Splenium , corpus callosum5-Pineal gland6-Cerebellum7-Tectum

*MRI :-Slightly higher signal than CSF on all sequences-A common incidental finding on MRI studies*T1 : -Typically iso to low signal compared to brain

parenchyma-55 to 60% are somewhat hyperintense when

compared to CSF-Generally homogenous signal

*T2 :-High signal -Usually slightly hypointense to CSF

*T1+C :-Approximately 60% of lesions enhance-Enhancement is usually thin (< 2mm) and confined

to the rim (either complete or incomplete)-It is important to note that if post contrast imaging

is delayed (60 - 90min), gadolinium may diffuse into the cyst fluid and may lead to the mass appearing solid

-In atypical cases enhancement may be nodular or there may be evidence of previous hemorrhage into the cysts

a) Sagittal T1+C shows an oval , low signal intensity , 20mm lesion in the pineal region , a finding consistent with a cyst , the lesion has a thin incomplete enhancing rim (arrow) , no nodularity of the wall and no associated hydrocephalus are seenb) Axial T2 shows an oval hyperintense lesion similar to CSF (arrow) in the pineal regionc) Axial FLAIR image shows that the signal of the lesion (arrow) is not completely suppressed due to the proteinaceous contents

T1+C shows a round low signal intensity 8 mm lesion in the pineal region , a finding consistent with a cyst , the lesion has a thin incomplete enhancing rim (arrow) , no nodularity of the wall and no associated hydrocephalus are seen

c) Differential Diagnosis :-A differential consideration is Pineocytoma

which would shows internal enhancement and may have cystic component, however a truly cystic Pineocytoma is considered very rare

2-Germ Cell Tumors :-Extragonadal germ cell tumors can be found in the pineal

gland as well as other intracranial and extracranial midline locations including the suprasellar region, mediastinum and sacrococcygeal region

a) Germinoma (most common)b) Teratomac) Embryonal Cell Carcinomad) Choriocarcinoma

a) Germinoma :1-Incidence2-Radiographic Features3-Tumor Markers

1-Incidence :-Most common pineal germ cell tumor (equivalent to seminoma in

testes and dysgerminoma in ovary)-Males predominate (10:1), age 10 to 30 years-In females, more commonly located in suprasellar location-10% have synchronous infundibular / suprasellar germinoma-Serum markers (alpha-fetoprotein) may also be positive-Sensitive to radiation therapy

2-Radiographic Features :a) CT -Well defined slightly hyperdense mass that

engulfs a prominent calcified pineal gland-Homogeneous intense enhancement-Central calcification due to pineal engulfment

(rare)

Axial nonenhanced CT shows a hyperattenuating lesion in the pineal region that has engulfed the pineal calcification (arrow)

Nonenhanced CT shows a partly calcified mass in the pineal region (arrow)

CT+C shows an enhancing mass in the pineal region which engulfs a calcified pineal gland

The tumor contains calcifications , there is homogeneous enhancement

b) MRI -T1 : isointense or slightly hyperintense to adjacent brain-T2 : isointense or slightly hyperintense to adjacent brain, may have

areas of cyst formation, central calcification appears low signal (engulfed pineal gland)

-T1+C : vivid and homogeneous-ADC : Low ADC (highly cellular)-MRI helps delineate local seeding to ventricles and distant seeding

of the subarachnoid space (spinal imaging is also required)

T1

T1+C

T1 T2

T1+C

Sagittal T2 shows a mass (black arrow) which is solid with small cysts , the tumor extends upward , compressing and displacing the internal cerebral vein (white arrows)

Axial T1+C shows a homogeneously enhancing mass in the pineal region

Sagittal T1+C demonstrates an enhancing mass in the pineal region , compression of the quadrigeminal plate and aqueduct is shown

Sagittal T1+C shows a mass which is solid with small cysts and marked enhancement

Axial T1+C shows an enhancing mass in the pineal region with bilateral extension into the posterior thalami

Suprasellar germinoma , sagittal T2 shows a solid mass with a cystic area ( arrow ) , The tumor extends upward toward the infundibular recess

Suprasellar germinoma , sagittal T1+C with fat saturation shows a solid mass with marked enhancement , the pituitary gland is compressed and flattened along the sellar floor (arrows) , the tumor extends upward toward the infundibular recess

**The following T1+C , Diffusion & T1+C show :-Germinoma in a 19 years old man with headaches(a) Sagittal postcontrast T1-weighted MR image shows a

lesion in the pineal region that homogeneously enhances , note the associated mild hydrocephalus

(b) Diffusion-weighted MR image shows high signal intensity in the lesion , a finding indicative of high cellularity

(c) Sagittal gadolinium-enhanced T1-weighted MR image shows nodular enhancing masses (arrows) along the cauda equina , findings consistent with drop metastases

Germinoma in a 19 years old man with headaches, (a) Sagittal T1+C shows a lesion in the pineal region that homogeneously enhances, note the associated mild hydrocephalus, (b) Diffusion-weighted MR shows high signal intensity in the lesion, a finding indicative of high cellularity, (c) Sagittal T1+C shows nodular enhancing masses (arrows) along the cauda equina, findings consistent with drop metastases

3-Tumor Markers : HCG AFP

Germinoma - -

Embryonal cell carcinoma

+ +

Choriocarcinoma + -

Yolk sac tumor - +

b) Teratoma :1-Incidence2-Radiographic Features

1-Incidence :-Second most common pineal germ cell tumor-Almost exclusively in male children-The most common congenital intracranial tumor

and are usually diagnosed prenatally-Presence of fat and calcification is diagnostically

helpful with little to no enhancement

2-Radiographic Features :*CT :-Demonstrates at least some fat and some

calcification which is usually solid / clump like-They usually have cystic and solid components,

contributing to an irregular outline, solid components demonstrate variable enhancement

CT without contrast , note heterogeneity due to multiple small cysts and area of calcification on anterolateral rim

CT without contrast demonstrates a heterogeneous mass in the pineal region extending anteriorly into the cistern of the velum interpositum , the mass contains several large chunks of calcification and a darker cystic appearing are (arrow head) , heterogeneity like this especially when there is lipid material and calcification is a hallmark of mature teratoma

CT+C , there is relatively homogeneous enhancement of the non-calcified solid portions of the tumor , the cystic region doesn’t enhance

*MRI :-T1 :-Hyperintense components due to fat and

proteinaceous / lipid rich fluid-Intermediate components of soft tissue-Hypointense components due to calcification and

blood products-T2 :-Mixed signal from differing components-T1+C :-Little or no enhancement-Solid soft tissue components show enhancement

Pineal teratoma in a 2-year-old boy , Axial (a) and sagittal (b) T1 show a large heterogeneous pineal gland mass (arrowheads) and severe obstructive hydrocephalus

Axial T1 shows a lobulated , heterogeneous lesion that contains an area of hyperintensity (arrow) , a finding consistent with fat

Sagittal T1 shows a lobulated mass in the pineal region with foci of T1 shortening due to fat and variable signal intensity related to calcification

Sagittal T1 shows grossly heterogeneous mass with large amounts of hyperintense lipid material , it extends anteriorly towards the cistern of velum interpositum and posterior 3rd ventricle , note the cystic region (*) , the signal void of internal cerebral veins (arrow head) is superior to the mass , but there is a thin rim of hypointensity encircling the mass , suggesting a tumor capsule

T1+C shows enhancement of the soft-tissue portions of the lesion

Ruptured pineal region dermoid

Ruptured pineal region teratoma , T1 shows multiple high signal intensity foci corresponding to the lipid droplets

Ruptured pineal region teratoma , T1 & T2 show a supernatant lipid layer floating on the heavier CSF in the superior portions of both lateral ventricles , on the T2 there are high and low signal intensity bands at the lipid interfaces caused by a chemical shift artifact

Ruptured Dermoid cyst in a 16 year old girl with altered mental status , T1+C shows a hyperintense lesion (arrowhead) projecting anterior to the splenium of the corpus callosum , the signal intensity of the lesion did not change after administration of contrast material , Linear low-signal-intensity structures can be seen within the lesion , a finding consistent with hair. Lipid-fluid levels are seen in the frontal horns of the lateral ventricles (arrows)

3-Choriocarcinoma, Yolk Sac Tumors and Embryonal Carcinoma :

-Are rare neoplasms-These neoplasms may have imaging findings

similar to those of other germ cell neoplasms or primary pineal neoplasms

-Evaluation of tumor markers assists in making the appropriate diagnosis

-These lesions may also hemorrhage, resulting in T1 shortening

Tumor Markers : HCG AFP

Germinoma - -

Embryonal cell carcinoma

+ +

Choriocarcinoma + -

Yolk sac tumor - +

a) Sagittal T1 weighted MR image shows an heterogeneous pineal region mass with foci of T1 shortening due to hemorrhage , note the associated hydrocephalusb) Axial postcontrast T1-weighted MR image shows that the pineal region mass also has an heterogeneous enhancement with foci of necrosis/cyst , involvement of the tectal plate and both thalami are also present (not shown) , evaluation of serum oncoproteins demonstrated high level of b-hCG , biopsy of the lesion revealed that it corresponds to Choriocarcinoma

3-Parenchymal Cell Tumors :a) Pineocytomab) Pineoblastoma

a) Pineocytoma :-No male predilection-Older age group, mean age 35 years-Slow growing, dissemination is uncommon-No helpful imaging features, cannot be

distinguished by imaging features from a Pineoblastoma

CT without contrast shows a large and relatively homogeneous mass in the pineal region with peripheral displacement of pineal calcification (arrows) , the mass has extended anteriorly along the velum interpositum , this is the exploded pineal appearance that suggests an intrinsic pineal parenchymal neoplasm

Pineal apoplexy secondary to a pineocytoma , Axial nonenhanced CT shows a hyperattenuating lesion with a posterior cystic component in the pineal region , there is anterior displacement of the pineal calcifications , a hematocrit level is noted within the cystic component (arrow) , a finding consistent with hemorrhage , hydrocephalus is also present

CT+C shows homogenous enhancement of the mass which assumes a triangular shape as it conforms to the contours of the pulvinar of the thalami and velum interpositum

T1+C shows heterogenous enhancement is seen , anteriorly , there is non-enhanced cystic region (*)

T1

T1

T2

T1+C

Sagittal postcontrast T1 shows an avidly enhancing mass in the pineal region with resultant hydrocephalus

b) Pineoblastoma :-Highly malignant PNET (Primitive Neuroectodermal Tumors)-In patients with trilateral retinoblastoma, Pineoblastoma may

develop in patients with familial and or bilateral retinoblastoma

-(Exploded calcifications) along outside of mass (peripherally), unlike germinoma which engulfs and induces calcification of the pineal gland

-Dense enhancement-Larger, more heterogeneous with much greater propensity for

local invasion and CNS dissemination

Axial nonenhanced CT shows a large pineal region mass with resultant hydrocephalus , the pineal calcifications are exploded toward the periphery (arrows)

T1

T2

T1+C

Trilateral retinoblastoma

4-Metastases :-Due to the lack of a blood brain barrier,

metastases to the pineal gland occur relatively commonly but rarely in the absence of a known malignancy

-Leptomeningeal disease is present in 2/3 of patients with pineal metastases

b) Extrinsic Pineal Mass :1-Gliomas2-Vein of Galen Aneurysm3-Meningioma4-Quadrigeminal Plate Lipoma

1-Gliomas :-Gliomas (most commonly astrocytomas) of

varying grade may occur in adjacent intra-axial structures such as the tectum, midbrain or splenium of the corpus callosum

Tectal Glioma :a) Incidenceb) Radiographic Features

A-Anterior Horn of the Lateral VentricleB-Caudate NucleusC-Anterior Limb of the Internal CapsuleD-Putamen and Globus PallidusE-Posterior Limb of the Internal CapsuleF-Third VentricleG-Quadrigeminal Plate Cistern (Tectal plate)H-Cerebellar VermisI-Occipital Lobe

A-Falx CerebriB-Frontal LobeC-Anterior Horn of Lateral VentricleD-Third VentricleE-Quadrigeminal Plate Cistern (Tectal Plate)F-Cerebellum

2-quadrigeminal plate cistern (Tectal plate)5-interpeduncular cistern9-optic nerve10-inferior colliculus12-hippocampus19-lens20- ICA21-medial rectus muscle22-lateral rectus muscle

1-Posterior commissure2-Habenular commissure3-Internal cerebral vein4-Splenium, corpus callosum5-Pineal gland6-Cerebellum7-Tectum (quadrigeminal plate)

a) Incidence :-Tectal plate gliomas are encountered in

children and adolescents-Usually low grade tectal tumor causing

aqueduct stenosis-Typically low grade astrocytoma with good

prognosis

b) Radiographic Features :-CT :-Typical CT finding is homogenous expansion of

tectal plate, isodense to grey matter with minimal enhancement in postcontrast image

CT shows non-communicating hydrocephalus , note the low density lesion of the tectal plate

-MRI :-Typically the tumors demonstrate expansion of the

tectal plate by a solid nodule of tissue*T1 :-Iso to slightly hypointense to grey matter*T2 :-Hyperintense to grey matter *T1+C :-Usually no enhancement-Higher grade tumors tend to be larger and tend to

enhance more vividly

T1

T1

T1

A, Sagittal T1 shows severe hydrocephalus with poor visualization of aqueduct and nonenhancing isointense diffuse tectal mass

B, Sagittal T1 shows 5 years later after shunting shows stable tectal lesion

T2

T2 FLAIR shows a tectal mass leading to obliteration of the cerebral aqueduct

T1+C shows a slightly hypointense tectal mass which does not enhance , the mass obstructs the aqueduct and is stable over 8 years

A, Sagittal T1+C shows nonenhancing tectal massB, 18 months later , sagittal T1+C shows an increase in size and

enhancement of the tectal mass , necessitating radiotherapy

T1+C

2-Vein of Galen Aneurysm :-Despite the name, a vein of Galen aneurysm

isn’t a true aneurysm, instead, it represents dilatation of the vein of Galen due to an arteriovenous fistula between the anterior or posterior circulation and the venous plexus leading to the vein of Galen

3-Meningioma :-The tentorial apex, adjacent to the pineal gland,

is a characteristic location for meningioma-The tentorial meningioma tends to depress the

internal cerebral veins, in contrast to a pineal-based mass which typically elevates the internal cerebral veins

4-Quadrigeminal Plate Lipoma :-At CT, lipomas have low attenuation, consistent

with fat-At MR imaging, they have the same signal

characteristics as fat (hyperintense on T1 with saturation on fat-saturated images)

-No enhancement is seen on postcontrast images

Quadrigeminal plate lipoma , (a) axial T1 , (b) sagittal T1 show a lobulated , hyperintense mass of the quadrigeminal plate , note the associated thinning of the posterior body (arrow) and splenium of the corpus callosum