Primary Central Nervous System HIV Infection Definition Neurologic complications directly attributable to primary infection of the CNS by human immunodeficiency virus-1 (HIV-1) Clinical Features Epidemiology Virus enters CNS early, may remain subclinical Neurologic complications develop in up to 50% of cases Increased risk with lower CD4 counts and high CSF viral load Presentation Primary infection: meningitis (more common), meningoencephalitis Affects 10% to 20% of patients during…

General Viral Effects on the Central Nervous System Definition CNS viral infection associated with clinical or laboratory evidence of neurologic dysfunction based on viral tropism Clinical Features Epidemiology Viruses: number one cause of encephalitis and meningitis Most cases: acute, self-limited Arboviruses: most common cause worldwide U.S. incidence: 3.5 to 7.4 cases per 100,000 people per year Specific host cell surface receptors facilitate entry Routes: hematogenous (most…

Cerebral Toxoplasmosis Definition CNS infection with Toxoplasma gondii , a ubiquitous obligate intracellular protozoan that parasitizes humans and animals Clinical Features Epidemiology Worldwide distribution with increased incidence in France, Central and South America Definitive hosts: cats 225,000 cases/year in United States; 5000 deaths/year Immunocompromised host: reactivation or new infection Tachyzoite proliferation leads to disease progression and parasitemia Primary cause of focal mass lesions in AIDS Encephalitis:…

Cerebral Cryptococcosis Definition Severe CNS fungal infections caused by the genus Cryptococcus ; includes meningitis and focal “cryptococcomas” Clinical Features Epidemiology C. neoformans : ubiquitous in soil, bird excrement, compost C. gattii : tropical/subtropical climates, North American western coast Eucalyptus trees primarily Primarily infects nonimmunocompromised persons Most common CNS fungal infection in immunocompromised (primarily C. neoformans ) Increased incidence: alcoholism, sarcoidosis, corticosteroids, immunosuppression/autoimmune First manifestation of…

Acute Purulent Meningitis Definition An acute inflammatory process involving leptomeninges and cerebrospinal fluid Clinical Features Epidemiology Approximately 2.5/100,000 (United States) each year Hematogenous spread most common Pneumonia with bacteremia Other routes Direct inoculation (trauma, procedures) Invasion (sinusitis, mastoiditis, oral infections) Birth to 1 month: Streptococcus pneumoniae, E. coli, Listeria monocytogenes 1 month to 29 years: Neisseria meningitidis > Streptococcus pneumoniae Haemophilus influenzae (now less common because…

Chordoma of Skull Base Definition Slow-growing, locally aggressive bone tumor; believed to originate from embryonic notochord rests (“ecchordosis physaliphora”), found incidentally in 1% to 2% of autopsies Clinical Features Epidemiology Rare tumor: 0.2% of all intracranial tumors; 3% to 4% of all primary malignant bone tumors Average age: 41 years (range: 7 to 78 years) 3:2 male/female ratio for skull base chordoma Presentation 25% to 35%…

Definition Hematogenous spread of a primary tumor originating outside the CNS to the brain or its coverings Clinical Features Epidemiology Most common brain tumors in adults Incidence of about 10 to 30 per 100,000 per year CNS metastases found in about 25% of patients who die of cancer Most common primary sites: lung (50%), breast (15%), skin (melanoma) (11%), unknown primary site (11%), kidney, GI tract…

Definition Benign developmental thin-walled cysts defined by type of epithelium and location Examples: epidermoid, dermoid, colloid, arachnoid, endodermal, and ependymal Clinical Features Epidemiology Constitute about 1% of intracranial masses Affect all ages No gender predominance Believed to result from developmental “entrapment”; rarely acquired Epidermoid and dermoid cysts may arise by inclusion of ectoderm into surrounding tissue Colloid cysts derived from endodermal epithelium in the rostral dorsal…

Definition Primary tumors of the brain and spinal cord arising from arachnoidal/pial melanocytic cells Melanocytoma: localized, low-grade, noninvasive Melanoma: malignant, invasive, mitotically active Clinical Features Epidemiology Very rare entities Wide age range, but most occur in the fifth decade You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles Become membership If you are a member. Log in here

Pituitary Adenomas Definition A neoplasm of the adenohypophysis Most common tumor of the pituitary gland Clinical Features Epidemiology 10% to 15% of all intracranial tumors Annual incidence: 0.2 to 2.8 cases per 100,000 About 20% to 30% of pituitary adenomas are nonfunctioning (nonsecretory) Hormone-secreting adenomas: prolactin (PRL) 25%, growth hormone (GH) 20%, and adrenocorticotropic hormone (ACTH) 10%, gonadotropins (follicle-stimulating hormone/luteinizing hormone; FSH/LH) 10% to 15%, thyroid-stimulating…

Definition Highly vascularized tumor composed of stromal cells and capillaries usually found in the cerebellum, brain stem, or spinal cord Clinical Features Epidemiology 1% to 2% of all intracranial tumors Most common in adults in third to fifth decades; can affect infants and children especially in association with von Hippel-Lindau (VHL) disease No gender predominance Majority are sporadic 25% are associated with von Hippel-Lindau disease (autosomal-dominant…

Germinoma Definition Radiosensitive neoplasm of young individuals arising in the pineal or suprasellar region with histopathologic and immunohistochemical features similar to testicular seminoma and ovarian dysgerminoma Clinical Features Epidemiology Germinomas account for about 3% of pediatric intracranial tumors 65% of all CNS germ cell tumors Twice as common in East Asia and Japan as in the United States Male predominance Presentation Males in late teens or…

Pineocytoma Definition WHO Grade I primary pineal parenchymal tumor; a well-circumscribed, slow-growing tumor composed of small uniform pinealocyte-like cells Clinical Features Epidemiology Account for 14% to 60% of pineal parenchymal tumors Age ranges from 10 to 65 years; mean age is 38 years old No gender predilection Presentation Symptoms related to location: compression of adjacent structures including cerebral aqueduct, tectal plate; occasionally protrude into the third…

Definition Malignant lymphomas arising independently within the CNS without evidence of systemic lymphoma; most PCNSLs are aggressive B-cell lymphomas Clinical Features Epidemiology Comprise between 1% to 5% of primary brain tumors Peak incidence in immunocompetent individuals between 55 to 75 years of age Slight male predilection: 3 : 2 Individuals with inherited or acquired immunodeficiency are predisposed to PCNSL AIDS Immunosuppression due to organ transplantation Wiskott-Aldrich syndrome Strong…

Schwannoma Definition World Health Organizatin (WHO) Grade I encapsulated nerve sheath tumor composed of differentiated Schwann cells; associated with neurofibromatosis type 2 or schwannomatosis Clinical Features Epidemiology 8% to 10% of all intracranial tumors Age range: 10 to 90 years of age with peak incidence in fourth to sixth decades Most are solitary and sporadic 4% are associated with neurofibromatosis type 2 or schwannomatosis Account for…

Meningiomas: Overview and General Characteristics Definition Neoplasms arising from meningothelial (arachnoidal) cells; are usually attached to the inner surface of the dura mater (dural-based tumors) Clinical Features Epidemiology Comprise about 25% to 30% of primary intracranial tumors Incidental finding 1.4% at autopsy All age groups affected; most common in middle-aged to elderly patients; peak in fifth to seventh decades More common in females (F : M ratio ranges…

Medulloblastoma Definition Malignant, embryonal tumor arising primarily in the posterior fossa of children Clinical Features Epidemiology Most common primitive neuroepithelial tumor (PNET) in CNS; 0.5 per 100,000 Peak incidence: 5 to 10 years; adults cluster in 30s 20% of brain tumors in children Most common malignant brain tumor of childhood Several familial/hereditary disorders associated with medulloblastomas Presentation Symptoms are mainly due to increased intracranial pressure, morning…

Ganglion Cell Tumors Definition Well – differentiated tumors of the CNS with mature neurons (ganglion cells) as a defining feature: includes ganglioglioma (ganglion cell tumor with a low-grade glial element), gangliocytoma (without a glial element), and anaplastic ganglioglioma (ganglion cells and anaplastic glial elements) Clinical Features Epidemiology 4% of primary brain tumors, ~0.2/100,000/year Most common in temporal lobe, but may arise throughout neuraxis More common in…

Choroid Plexus Papilloma Definition Intraventricular papillary neoplasm; most common in children World Health Organization (WHO) Grade I Clinical Features Epidemiology Comprise 0.3% to 0.6% of brain tumors; 2% to 4% of pediatric brain tumors Most common in children under the age of 15 Account for 10% to 20% manifesting before the first year of life Lateral ventricular tumors arise in younger patients (<20 years) Fourth ventricle…

Angiocentric Glioma Definition Low-grade glial neoplasm (WHO Grade I) arising in childhood and typically associated with epilepsy; key pathologic features include angiocentric growth and monomorphous spindle cells; also called monomorphous angiocentric glioma and angiocentric neuroepithelial tumor Clinical Features Epidemiology Rare neoplasm arising in children and young adults (mean age 17 years) No gender predilection Typical locations: superficial cortical regions of the frontoparietal lobe and the temporal…