Neurology · Brain Tumors
The facts most likely to be tested
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Meningiomas are the most common benign primary intracranial tumor in adults, typically arising from the arachnoid cap cells of the meninges.
Imaging characteristically reveals a dural-based, well-circumscribed mass that demonstrates intense, homogeneous contrast enhancement.
The classic radiographic finding is the dural tail sign, representing thickening of the dura mater adjacent to the tumor.
Histopathology reveals psammoma bodies, which are concentric, laminated calcifications within the tumor tissue.
These tumors are frequently associated with NF2 (Neurofibromatosis type 2), especially when presenting as multiple lesions.
Patients often present with focal neurologic deficits or seizures due to the mass effect of the tumor compressing the underlying cerebral cortex.
Asymptomatic, small meningiomas are often managed with serial neuroimaging (observation), while symptomatic lesions are treated with surgical resection.
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A 55-year-old woman presents to the clinic with a 6-month history of progressive headaches and a recent focal seizure involving her left arm. Neurologic examination is significant for mild left-sided hemiparesis and hyperreflexia. MRI of the brain reveals a well-circumscribed, extra-axial mass attached to the falx cerebri. The lesion shows intense contrast enhancement and a prominent dural tail sign.
What is the most likely diagnosis?
Meningioma
The presence of a dural-based, extra-axial mass with a dural tail sign is pathognomonic for a meningioma, which is the most common benign intracranial tumor in adults.
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Etiology / Epidemiology
Most common benign primary intracranial tumor in adults, typically arising from the arachnoid cap cells.
Clinical Manifestations
Often asymptomatic; focal deficits or seizures occur due to mass effect and peritumoral edema.
Diagnosis
MRI with gadolinium is the gold standard; classic finding is the dural tail sign.
Treatment
Surgical resection is the definitive treatment for symptomatic lesions; observation for small, asymptomatic tumors.
Prognosis
Generally favorable; WHO Grade I tumors have high cure rates, but recurrence is possible if resection is incomplete.
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Epidemiology & Etiology
Incidence increases with age, peaking in the 6th and 7th decades. Females are affected more frequently than males, often linked to progesterone receptor expression. Prior cranial radiation is a well-established environmental risk factor.
Pertinent Anatomy
These tumors arise from the arachnoid cap cells of the meninges. They are typically extra-axial, compressing the underlying brain parenchyma rather than invading it. Common locations include the parasagittal region, falx cerebri, and sphenoid wing.
Pathophysiology
Meningiomas are slow-growing, encapsulated neoplasms. They exert clinical effects primarily through mass effect and compression of adjacent structures. They may induce significant peritumoral edema, which correlates with the severity of neurological symptoms.
Clinical Manifestations
Presentation is often insidious, including headaches, focal seizures, or progressive neurological deficits. Psammoma bodies are a classic histological feature. Seizures and progressive focal weakness are common red flags requiring urgent imaging.
Diagnosis
MRI with gadolinium contrast is the diagnostic modality of choice. The pathognomonic finding is the dural tail sign, representing thickened, enhancing dura mater adjacent to the tumor. CT scan may show hyperostosis of the overlying bone.
Treatment
Asymptomatic, small tumors are managed with serial imaging. Symptomatic or growing tumors require surgical resection. Radiation therapy is reserved for unresectable, malignant, or recurrent cases. Antiepileptic drugs are indicated only if the patient has experienced a seizure.
Prognosis
Most are WHO Grade I and carry an excellent prognosis following gross total resection. WHO Grade II (atypical) and Grade III (anaplastic) variants have higher rates of recurrence and require closer monitoring with serial MRI.
Differential Diagnosis
Glioblastoma: rapid progression and central necrosis
Brain Metastasis: usually multiple lesions with surrounding edema
Schwannoma: typically involves the cerebellopontine angle
Dural AV Fistula: vascular flow voids on MRI
Primary CNS Lymphoma: usually periventricular and enhances homogeneously