Falx Lesions
Miral D. Jhaveri, MD
DIFFERENTIAL DIAGNOSIS
Common
Physiologic Calcification, Dura
Osseous Metaplasia
Subdural Hematoma, Acute
Meningioma
Metastases, Meningeal
Less Common
Neurosarcoid
Extra-Axial Empyema
Rare but Important
Intracranial Hypotension
Hypertrophic Pachymeningitis
Erdheim-Chester Disease
Rosai-Dorfman Disease
Extramedullary Hematopoiesis
Chondrosarcoma
Solitary Fibrous Tumor
Hemangiopericytoma
Dural A-V Fistula
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Smooth dural thickening, enhancement usually benign
“Lumpy-bumpy” not always malignant!
Helpful Clues for Common Diagnoses
Physiologic Calcification, Dura
Common in the middle-aged/elderly, falx or tentorium
Dense amorphous Ca++ plaques
Osseous Metaplasia
Different from simple “dense dural calcification” on NECT
Look for cortex and medullary space (bone CT)
Most common in anterior/mid-falx
Mottled hyperintensity (T1WI) surrounded by hypointense dense cortex (T2WI)
“Blooms” on GRE
True falx lipoma rare (look for chemical shift artifact)
Subdural Hematoma, Acute
Can be isolated; may extend along convexities, tentorium
Look for signs of nonaccidental trauma (shaking) in children with interhemispheric SDH
Meningioma
Common location for meningiomas
Most arise along middle 1/3rd of the superior sagittal sinus (SSS)
May grow into, occlude SSS
Look for “dural tail” sign
Metastases, Meningeal
Can mimic meningiomas
Helpful Clues for Less Common Diagnoses
Neurosarcoid
Nodular, “lumpy-bumpy” falx
Extra-Axial Empyema
Frontal sinusitis → empyema ± posterior extension along falx
Rim-enhancement, restricts on DWI
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