Ch. 7 - Benign brain tumors Flashcards
What layer of the meninges do meningiomas arise from?
Arachnoid layer (arachnoid villi and granulations)
Most common benign brain tumor
Meningioma (15% of all intracranial tumors, peak incidence in middle age, women > men)
Etiology of meningioma
Head trauma, irradiation, NF-2 (esp. multiple meningiomas), female gender is risk factor (hormonal?)
Most common meningioma locations
Parasagittal region (superior sagittal sinus or falx) > posterior fossa convexity > sphenoidal wing
If multiple meningioma are present, what is the most likely etiology?
NF-2
What is the meningioma classification system based on?
Position of origin, NOT histology
Psammoma bodies
Whorls of cells which may undergo hyaline degeneration with subsequent deposition of calcium salts; seen in transient type meningiomas
Clinical presentation of meningioma
Raised ICP, focal neurological signs, epilepsy
Meningiomas are typically fed by what artery?
External carotid artery
Preoperative tx of meningiomas
High-dose steroids for severe cerebral edema
What characterizes BENIGN brain tumors?
Do NOT invade underlying parenchyma
Classic feature of meningioma on plain radiograph
Hyperostosis of cranial vault
Tx of meningiomas
Total surgical excision, including obliteration of dural attachment
Meningioma recurrence after surgery
Rare if completely excised; most common source of recurrence is from tumor that invaded venous sinus which was not resected
Identify the lesion
Typical vault meningioma
Why is the term ‘acoustic schwannoma’ a misnomer?
Arises from vestibular component of CN8; should be called vestibular schwannoma
Presenting features of acoustic schwannoma
Tinnitus and unilateral partial or complete sensorineural hearing loss
What happens during Hallpike caloric testing (irrigate ear canal with cold water) in patient with acoustic schwannoma?
Nystagmus is depressed or absent on side of tumor
Surgical options for cerebellopontine approach in resection of acoustic schwannoma
Excision of labyrinth OR
Posterior fossa craniectomy OR
Middle cranial fossa approach
Complications of acoustic schwannoma excision
Hearing loss (esp. with translabyrinthine approach), facial paralysis if CN7 damaged, sensory abnormalities if CN5 damaged
Identify the lesion
Acoustic schwannoma at cerebellopontine angle
Identify the lesion
Bilateral acoustic schwannomas in NF-2
What genetic syndrome is associated with intracranial hemangioblastomas?
Von Hipple-Lindau’s disease, though most patients with these tumors do not have the syndrome
Unique presenting feature of intracranial hemangioblastoma
Polycythemia 2/2 increased circulating erythropoietin
Typical location of intracranial hemangioblastoma
Cerebellum
Describe the location and features of colloid cysts
Cyst containing gelatinous material, situated in anterior part of 3rd ventricle; causes obstruction of foramina of Monro leading to hydrocephalus
Identify the lesion
Colloid cyst of 3rd ventricle
What are epidermoid and dermoid cysts? Where are they most commonly found intracranially? How do they appear histologically?
Epithelial cells embryologically displaced; found principally in arachnoid spaces, cisterns, or skull
Epidermoid cyst - desquamated epithelium with keratin-producing epithelium
Dermoid cyst - includes dermal elements (e.g. hair follicles, sebaceous glands)
