Phakomatoses Flashcards
Phakomatoses are characterized by:
- Hamartomas and Congenital Malformations affecting structures of ectodermal origin (visceral organs to a lesser extent)
- Ectodermal Origin:
- Nervous system
- Skin
- Globe
- Retina
- Ectodermal Origin:
What are 6 Inherited Cancer Predisposition Syndromes in which exposure to ionizing radiation should be minimized?
- Ataxia-telangiectasia
- Hereditary retinoblastoma
- Li Fraumeni syndrome
- Neurofibromatosis type 1
- Nevoid basal cell nevus syndrome
- Nijmegen breakage syndrome
NF1 gene is what?
Tumor supressor gene expressed in neurons, schwann cells, oligodendrocytes
Of patients with NF1 - will most develop OPGs?
No, only 15%
Of patients with OPGs, do most have NF1?
No, 40%
Is unilateral or bilateral involvement of an OPG classic for NF1?
Bilateral
What does FASI stand for? How is it defined?
- Focal Area of Signal Intensity - caused by Myelin Vacuolization (layers of myelin become separated as they spiral around the axon)
- No mass effect,
- No contrast enhancement
- No hemorrhage
- Increased diffusivity on DWI
What is this? Where are they usually found?
- FASI (in NF1) - Focal Area of Signal Intensity
- Found in globus pallidus, Internal Capsule, Corona radiata, Thalami, Deep cerebellar nuclei.
- NOT found in subcortical white matter/centrum semiovale
True or false: OGPs in NF1 are more likely to include primary involvement of the optic nerve (vs only the chiasm and optic radiations)
True - sporadic cases of OPG are more likely to involve only the chiasm/radiations and have a worse prognosis vs. indolent course of NF1 OPGs involving only optic nerve
Which course of OPG is more indolent: NF1 or sporadic?
NF1 (worse prognosis if sporadic)
What is the treatment for OPG in patients with NF1?
OPGs are low histological grade (pilocytic astrocytomas). They may even regress in patients with NF1. So - treatment should not be aggressive - wait to see if symptomatic/radiologic progression
How to differnetiate OPG from FASI?
OPGs have contiguity, mass effect, low T1 on post-contrast, enhancement after contrast, elevations in choline on MRS
What is an appropriate protocol for assessment of the Orbits in NF1?
Hi-res (<3mm) T1 and T2 FS axial/coronal sequences through globes, optic nerves, chiasm, followed by T1 FS - post Gad axial/coronal images. Followed by routine brain.
Where can an OPG extend when beyond the optic pathway?
- superiorly: into hypothalamus, fornices, septum pellucidum
- Laterally: Temporal lobes
- Posteriorly: Optic radiations
- Inferiorly: into crebral peduncles/brain stem.
Is this spectroscopy from a FASI or OPG?
OPG (increased choline to creatine ratio)