 Now moving on from that let's move to primitive rest cell kind of tumors now This is this entails conditions when you have mesenchymal things epidermal endodermis all contribute and depending on which Cell line contributes you can classify into different entities and that would be between dermoid teratoma epidermoid and accordingly, so let's move on of these the primitive cell origin neoplasm We are going to be briefly talking about epidermoid dermoid and teratoma the first one being epidermoid This is more frequently encountered than the other neoplasms This is essentially because of an ectodermal inclusion during neural tube closure in a congenital form This can be congenital as well as acquired so Congenital would be during the neural tube closure. There is ectodermal inclusion Which gets trapped inside the intracranial portion. This can easily be an acquired entity where related to prior surgery or trauma Ectoderm can get included and it causes an epidermoid formation Histologically it is identical to what we see as in cholesterol toma now This can happen anywhere along the entire neural axis wherever the neural tube closure happened So it can be dorsal to the spinal cord or it can be within the intracranial portion It tends to be centrally located rather than peripheral But it can happen anywhere in the brain most common location of this is generally at the CP angle In fact all dermoid be dermoid and teratoma all three all of these congenital neoplasms tend to have their location centrally and among centrally more frequently in the cellar supercellar and CP angle region majority of the cases happen to be in this location now in Appearance this can be Frequently missed if it is small in size if it is large in size on CT It is seen as a CSF density and MRI on T21. It is seen as CSF intensity Legion this has a minimal mass effect not much for the size of the epidermoid But it appears as a lobulated kind of bubbly kind of appearing lesion along the border with Saculations around the border which tends to insinuate along the margins of the brain and it encases rather than Displace which would be seen displacement would be seen in a clear system But this is a lobulated kind of tumor which is growing along it completely encases the subjects and vessels or nerves the two classic Sequences that are used to differentiate this from other entities are Diffusion sequences and flair sequences on the flair it has a kind of a dirty appearance It is called as the dirty CSF sign on T1 and T2 it can be clearly missed as a complete CSF intensity Where it will be difficult to differentiate between an anachnoid cyst or says Neurocystisurcosis when it is small but on flair it will have a dirty CSF sign But on the the hallmark of this is being restricted a fusion where it is like a light bulb Which stands out within the brain parent camera? So it can be clearly differentiated from all other entities like Erechnoid cyst or Neurocystisurcosis or any other causes of Existing along the Intercranial portion so the study of choice through diagnosis and epidermoid is Diffusion sequence and even on post resection when the neoplasm has been decompressed or excised The main sequence that you use to look for any recurrent or residual epidermoid would be a diffusion sequence and Moving on from an epidermoid tumor Let's go on to the second form which is the dermoid tumor now both Epidermoid and dermoid are strictly Ectodermal in nature The difference between the two is epidermoids is entirely from squamous salepithelium Where is the dermoid has both squamous salepithelium as well as dermal appendages which include Subitious and sweat glands and hair within it producing sebum which gives us the characteristic appearance now There is a very common misconception that there is fat inside dermoids now adipose tissue is a mesodermal component It is not an epidermal there is dermoid strictly speaking a dermoid has Ectodermal origin so the thing that is present inside the sebum would be including cholesterol hair cells Subitious glands keratin squamous epithelium and a protein byproducts would be giving the hyper intensity one signal intensity and That is what we see on Classically the imaging on CT it is classically a low attenuation lesion with fluid fluid level related to debris can potentially have Calcification which can be chunky Calcification which can be a tooth like calcification which can be a central calcification or it can be a circumferential peripheral Calcification if we see a tooth inside of the lesion a low attenuation Lesion with fluid fluid level that is the hallmark unless proven. Otherwise, it is going to be a dermoid cyst You know CT is a low attenuation kind of a fat density lesion Lobulated mass with calcification which can be rim or chunky calcification and MR is much much more Variable can be predominantly. It is a hyper intense lesion on T1 with fluid fluid level Because of cholesterol present whereas on T2 it is very very variable. It can be hyper intense to hyper intense in nature There is a fluid level present the important thing to note about it is that this is a lesion that grows Because there is constant secretion from the sebaceous glands and the sweat glands There's content in coast low increase in size and because of that there is a progressive increase in mass effect And it can potentially rupture and when it does rupture there is these hyper intense droplets which are seen Diffusely within the CSF spaces in this being lighter than a CSF It tends to float superiorly rather than being in a dependent portion so if we'll as we see over here in the lateral ventricles that D1 hyper intensities are floating in the frontal horn and In the second case it is dispersed throughout But if we look at it majority of it been eventually when the patient is supine will float up anteriorly this causes severe chemical meningitis and potentially if not almost always fatal because of the severe chemical meningitis So on CT it is low to fat attenuation With calcification associated with the tooth and hair cells within it and on MR It is a very variable intensity But there are components of susceptibility or calcification and T1 hyper intensity and when it ruptures this same T1 hyper intensity from cholesterol floats up superiorly along the non dependent portion Moving on to the next form of primitive or congenital cell line tumor We would be talking about teratoma now as we talked about in Dermoid and epidermoid which is epidermal in location or in the origin Teratoma on the other hand contains two or three layers of the dermal elements It may it has to at least contain two layers and maybe it may contain all three layers of the Dermal elements. This is a more aggressive form of neoplasm as opposed to dermoid and epidermoid It has solid and a cystic component both on CT and MRI The appearance can be described very in a very similar fashion So you will see a solid cystic component It will have calcification not the kind of calcification like the chunky prominent Calcification as we saw in dermoid, but there will be associated Calcifications with this it will be a solid tumor. It will be a cystic tumor Component with it as we talked about in dermoid and epidermoid these tend to be centrally located the frequent locations being the pineal region The supercellar region the Cp angle region. These would be the typical locations We see a solid cystic mass in this area with calcifications We should think of teratoma as opposed to the first two tumors the solid component in a teratoma will show enhancement This is a lesion which was lipid rate So this will actually truly have fat cells within it because it is arising from at least two layers Fat being mesenchymal in origin. So this is an example on a CT where we see a solid Slash cystic mass lesion with areas of calcification Situated in the pineal gland area and it is causing obstructive hydrocephalus Probably because of compression on the aqueduct of sylvia. So this is again This is something that we have to talk about the hydrocephalus. This is what can decompensate the patient very quickly So this is a patient who should not go home It is a patient who we have to call the clinician and tell them Whether he should be sent to the ER or should be sent to the clinic because this patient can decompensate quickly and die So this on MR imaging is again the same description where it is a solid cystic component The T1 hyperintensity here is actually truly fat because the mesenchymal is Aligning is in this neoplasm. Now. This is again situated along the CSF outflow path So it is again causing hydrocephalus on contrast administration. This would have Associated enhancement in the solid component the fallout of signal which we are seeing on the T1 sequences is because of the calcification Present within this region. So as opposed to dermoid, there will be no fluid fluid level in this thing Dermoid the classic finding is a fluid fluid level here. It is completely absent It is a purely solid and a cystic Lesion with enhancement and with calcification. So that is how we would see term term now This is a relatively aggressive tumor. It is something that can be associated with drop metastasis So one of this shows up on your MR scanner It is our obligation to make sure that we aim is the entire neural axis to look for any drop metastasis or an Associated leptomine in gel enhancement as opposed to what it would not be necessary in the case of epidermoid or dermoid lesions Moving on to the final type of primitive cell line tumor. We would be talking about germinoma now germinoma is Very similar to other tumors like a lymphoma or primitive new recto dermal tumor Basically because of histology, this is a round blue cell tumor So it will be a high nucleus cytoplasmic ratio densely packed cells. So this would be in appearance Very very similar to in imaging characteristics very very similar to what we would see in a primitive new recto dermal tumor or lymphoma where We will see a dense lesion on CT I saw to a hyper intense mass on T1 and T2 sequence which was intense enhancement This tumor is also called as a dis germinoma or an extra gonadal Seminoma and like all the other primitive cell line tumors This is also something that tends to be in the midline Predominantly it happens in mid pediatric patients So the typical locations are in the pineal gland region or the third ventricular inferior third ventricular region or supercellar region Classic being within the pineal gland region. So this would be a like a lobulated soft tissue mass Which is sitting in the pineal gland region. Typically it entirely engulfs the pineal gland and with because of that There might be a central chunky calcification of that central chunky calcification is what would differentiate that it is engulfing The pineal gland rather than inherently pineal gland new plasma where the calcification in those tumors like pineal cytoma or pineal blastoma It would be a burst calcification as opposed to a germinoma where it will be a central calcification So on imaging on CT. It is a hyper dense lesion on MR It is a high ISO to hyper intense both on T1 and T2 sequences There may be small areas of hemorrhage, but not a clear large in hematoma it tends to engulf the surrounding structures as well as cause mass effect and In when it is situated in the region of pineal gland, there might be a chunky calcification Which is actually the calcification the pineal gland when you give contrast to this new plasma like what we see in lymphoma and peanuts This there will be an intense associated enhancement. So all this is a non-contrast CT examination It is a hyper dense machine lobulated mass lesion This one is sitting in the supercellar region or the inferior third ventricular region Moving on to the MR. This is an enhancing Intensely enhancing mass lesion to separate tumors the first and the third sequences are in the region of the supercellar third ventricular area The second slide is of a new plasma sitting in the pineal gland region Now this is again a new plasma which is in the CSF region So this is a lobulated soft tissue debris kind of new plasma sitting So as we talked about in Coroate Plexus papillary carcinoma as we talked about in medial blastoma This is another tumor that we have to image the entire neural axis because this is something that would be causing drop metastasis Also, it would cause hydrocephalus both because of cellular debris as well as because of obstruction direct obstruction So tumor sitting in the region of pineal gland would directly push on the quadrigeminal plate and cause obstructive hydrocephalus Due to compression of the aqueduct of acid gas So lesion which is intensely enhancing sitting in these classical locations with the restricted diffusion is Undisproven otherwise a germinoma and we have to do look for on restricted diffusion as well as we have to do the entire neural axis Imaging to look for potential drop metastasis. So those are pretty much cover or A new plasma rising from primitive cells now There are a whole bunch of other new plasma, but those three or four entities constitute 99% of the new plasma arising from primitive cell lines and are typically found in the central portion of the brain along the Midline although can happen anywhere, but classically they are present along the center line Let's talk about new plasms that arrived from arachnoid cell line So the classic one or the most common one would be the arachnoid cyst now, this is not a true neoplasm This is an entirely benign entity This can be both congenital in nature or it can be acquired related to a tear in an arachnoid Aligning so what happens is there's a confined arachnoid lined CSF cyst collection There is no communication with the ventricles This is completely independent most common typical location is within the CP angles or within the middle cranial fasa and It follows CSF intensity on all sequences So that is what would be differentiating this entity from which we talked about previously That is the epidermoid cyst So the two main things that we talked about in cases of epidermoid are the dirty CSF sign on flare sequences Which would not be present over here, but it would be even on flare sequences entirely clear dark following CSF intensity and The restricted diffusion which we talked in epidermoid where there is intense restricted diffusion here This is not associated with any restricted diffusion It will be dark on diffusion sequences with CSF intensity on all sequences and We what we might potentially see is there might be a pulsation artifact Related to the phase region as well as since this is a long-standing thing There's constant pulsations on the subject and boom. So there'll be associated bone scaloping They'll be associated mild mass effect on the brain pattern Kaima related to this being assist staying in a confined Calvary and one of the important things that we have to Understand is this still communicates with the CSF. So if you inject dye like in a milogram Immediately the CSF will entirely fill up with contrast Whereas this would not be filling up with contrast immediately But you get a delayed examination because of its communication eventually This will also fill up with contrast and you will see that this is actually a system Which communicates with the CSF spaces confirming this is an Erechnoid system So we saw that that was an Erechnoid system a CT examination This would be an Erechnoid system MR examination. So a huge CSF intensity on all sequences Within the right convexity. This is the typical location within a second slice where it is in the situated within the middle cranial fossa and the same one to differentiate from an epidermoid We did a diffusion sequence where there is absolutely no restricted diffusion Which if this was an epidermoid would be associated with light bulb restricted diffusion So this causes pushing of the entire brain parent Kaima Scaloping of the bone buckling of the grave by distinction These are all the things that you use to describe an Erechnoid cyst again It is CSF intensity in all sequences if it is big enough it causes mass effect There is thinning of the bone because of constant CSF pulsations. That is the most common thing that we see in fact Probably about like 99% of the legion that we see in relation to the Erechnoid cells And it is a very very common tumor most of the time is incidental most of the time you don't have to do anything with it unless the patient is presenting with severe headache and This is what we are seeing then the surgeon goes in causes Creates a fenestration or puts in a drainage catheter in it like a short catheter in it and decompresses it So if it is causing mass effect if it is causing herniation if it is causing any Displacement of brain parent Kaima or if it is associated with headaches then those are the possible treatment where you create a fenestration and you or you can put in a Shunt catheter and then down subsequent examination the patient will probably come back to you for follow-up Evaluation to look whether it is being effective or not