Thick Septum Pellucidum
Karen L. Salzman, MD
DIFFERENTIAL DIAGNOSIS
Common
Cavum Septi Pellucidi (CSP)
Astrocytoma
Less Common
Lymphoma, Primary CNS
Germinoma
Metastasis, Intraventricular
Neurofibromatosis Type 1
Rare but Important
Alexander Disease
Fused Fornices (Holoprosencephaly)
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Septum pellucidum should be 2 mm or less
Any neoplasm with propensity for ependymal/subependymal spread may cause thickened septum pellucidum
Helpful Clues for Common Diagnoses
Cavum Septi Pellucidi (CSP)
Cystic CSF cavity of septum pellucidum between frontal horns, normal variant
Follows CSF on all sequences
May have associated mass effect
Astrocytoma
Often involves septum pellucidum from ependymal spread or corpus callosum
Primary tumor of septum pellucidum rare
Imaging varies with tumor grade
Helpful Clues for Less Common Diagnoses
Lymphoma, Primary CNS
Enhancing lesions in basal ganglia or periventricular white matter typical
Often extend along ependymal surfaces
Germinoma
Ventricular disease related to CSF seeding
Primary intraventricular germinoma, rare
Metastasis, Intraventricular
May involve septum pellucidum by ependymal spread
Gray-white junction lesions most common
Neurofibromatosis Type 1
Thickening related to presumed hamartomatous involvement of forniceal columns as they pass through septal leavesRelated posts:
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
