Originate in the subpial astrocytes typically in children and young adults often with a seizure history
Temporal lobe is most common
Imaging (variable):
▶️Classically appear as a cortically based mass with cyst and enhancing nodule and overlying DURAL TAIL or enhancing leptomeninges
▶️Calcifications are RARE
▶️Can look very similar to ganglioglioma though calcifications are rare in PXA and if you’re lucky enough to have a dural tail/enhancing leptomeninges then PXA is favored
▶️Companion case of another PXA below
2️⃣DNET
▶️Cortically based mass in children and young adults presenting with long-standing seizures
▶️Most frequently occurs in temporal and frontal lobes
Imaging:
▶️Classically presents as a well demarcated cortically based “BUBBLY” mass with HYPERINTENSE RIM AROUND CYSTS ON FLAIR
▶️Usually there is NO ENHANCEMENT (though can have punctate or ring enhancement). However, when enhancement is seen, consider the possibility of more aggressive tumors.
▶️Companion case below of another DNET
3️⃣Oligodendroglioma
▶️Cortically based mass mainly in ADULTS
▶️Location: FRONTAL and temporal lobes most common
Imaging:
▶️Classically presents as a gyriform cortical/subcortical based mass with GYRIFORM OR CLUMPED CALCIFICATIONS
▶️Consider this diagnosis in an ADULT WITH A CALCIFIED FRONTAL MASS
4️⃣Ganglioglioma
▶️Occurs in children and young adults
▶️Location: Temporal lobe (most common)
Imaging (variable and can look very similar to PXA):
▶️Classically presents as a cystic and solid mass in the temporal lobe in a child/young adult with seizures
▶️Presence of CALCIFICATIONS & LACK OF DURAL TAIL may help to differentiate from PXA
Companion case of another ganglioglioma
💡 Learning points/summary:
P-DOG 🐶
1️⃣PXA: Cyst w/ enhancing mural nodule with DURAL TAIL/leptomeningeal enhancement and NO CALCIFICATIONS
2️⃣DNET: BUBBLY well demarcated mass with NO ENHANCEMENT
3️⃣Oligodendroglioma: Gyriform mass in frontal lobe of an ADULT w/ CALCIFICATIONS
4️⃣Ganglioglioma: Cyst w/ enhancing nodule in temporal lobe w/ CALCIFICATIONS and NO DURAL TAIL
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▶️Susac syndrome is a microangiopathy (likely autoimmune affecting the precapillary arterioles) with a strong female predilection, typically occurring in women age 20-40
Clinical presentation:
Classic triad
1️⃣Encephalopathy
2️⃣Branch retinal artery occlusions
3️⃣Hearing loss
💡Though most patients do not present with the complete triad (it may develop over years)
▶️Biopsy showed a reactive and reparative osseous process and bone culture grew oral flora (though cultures are usually negative)
▶️SOG is thought to be due to a low grade infection possibly 2/2 dental disease. However, there should be no signs of acute infection (suppuration, bony sequestration or draining tracts)
▶️Initial non-con CT shows a 3cm hyperdense lobulated extra-axial mass in the expected region of the left MCA bifurcation, consistent with a giant aneurysm. There are associated peripheral calcifications
▶️ What is the cause of the surrounding hypodensity?