Cavernous Malformation

KEY FACTS

TERMINOLOGY

• Cavernous malformation (CM)

• Benign vascular hamartoma

○ Contains masses of closely apposed immature blood

vessels ("caverns"), no neural tissue

○ Intralesional hemorrhages of different ages

IMAGING

• General: Locules of variable size with blood at different

stages of evolution

○ Variable appearance depending on hemorrhage/stage

○ CMs vary from microscopic to giant (> 6 cm)

• Classic MR: Popcorn-ball appearance with complete

hypointense hemosiderin rim on T2WI MR

• DSA: Usually normal (angiographically occult vascular

malformation) unless mixed with DVA

• Zabramski classification of CMs

○ Type 1 = subacute hemorrhage (may obscure underlying

CM)

○ Type 2 = mixed signal intensity on T1, T2WI (classic

"popcorn ball" lesion)

○ Type 3 = chronic hemorrhage (hypo- to isointense on T1,

T2WI)

○ Type 4 = punctate microhemorrhages (blooming "black

spots" on T2* GRE, SWI)

TOP DIFFERENTIAL DIAGNOSES

• Arteriovenous malformation

• Hemorrhagic neoplasm

• Calcified neoplasm

• Hypertensive microbleeds

• Amyloid angiopathy

CLINICAL ISSUES

• Variable behavior (enlarge, regress, form de novo)

• All ages (peak = 40-60 years)

• Can be cerebrum (most common) or posterior fossa (most

serious); symptoms are neurological deficits

(Left) Axial graphic depicts

various stages of cavernous

malformations with subacute

hemorrhage ﬉ and classic

"popcorn ball" ﬊ lesion with

multiple blood-filled locules,

surrounding hemosiderin rim.

Multifocal "blooming black

dots" ﬈ are also depicted.

(Right) Axial NECT scan shows

a mixed-density right thalamic

mass with edema. Note fluidfluid level ſt within the mass.

(Left) Axial T2WI in the same

case shows the classic

popcorn-ball appearance of a

cavernous malformation with

multiple fluid-filled locules ſt.

A second, separate lesion is

also present ﬇. (Right) T2*

GRE scan in the same case

shows striking "blooming" in

and around the 2 lesions ﬊. A

3rd lesion ﬉ in the right

occipital lobe is present but

was difficult to see on the

standard FSE T2-weighted

sequence.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

121

Capillary Telangiectasia

KEY FACTS

TERMINOLOGY

• Brain capillary telangiectasia (BCT)

• Cluster of enlarged, dilated capillaries interspersed with

normal brain parenchyma

IMAGING

• General features

○ Common sites: Pons, cerebellum, spinal cord

○ Usually < 1 cm

• CT

○ Usually normal

• MR

○ T1WI usually normal

○ T2WI

– 50% normal on T2WI

– 50% show faint stippled foci of hyperintensity

○ Large BCTs may show ill-defined FLAIR hyperintensity

○ Moderately hypointense on GRE; profoundly

hypointense on SWI

○ T1 C+ shows faint stippled or speckled brush-like

enhancement

○ Large BCTs typically contain prominent linear draining

vein(s)

TOP DIFFERENTIAL DIAGNOSES

• Developmental venous anomaly

• Metastasis

• Cavernous malformation

• Capillary hemangioma

CLINICAL ISSUES

• BCTs represent 15-20% of all intracranial vascular

malformations

• Usually found incidentally at autopsy or imaging

• Rare: Headache, vertigo, tinnitus

• Clinically benign, quiescent

○ Unless histologically mixed (usually with capillary

malformation)

(Left) Axial gross pathology

shows a large capillary

telangiectasia of the pons. The

dusky color ﬊ is caused by

deoxygenated blood, not frank

hemorrhage. Note undisturbed

transverse pontine tracts ﬉

crossing the telangiectasia.

(Right) Axial T2WI in a

neurologically normal patient

with headaches shows very

faint "stippled"

hyperintensities in the central

pons ﬇.

(Left) Axial T2* GRE in the

same patient shows faint

hypointensity in the central

pons ﬊. (Right) Axial T1 C+

MR in the same patient shows

faint brush-like enhancement

﬇ in the central pons,

characteristic of a large

capillary telangiectasia.

(Courtesy P. Rodriguez, MD.)

Neoplasms

Neoplasms Overview 124

Astrocytomas

Low-Grade Diffuse Astrocytoma 128

Anaplastic Astrocytoma 129

Pilocytic Astrocytoma 130

Glioblastoma 131

Gliomatosis Cerebri 132

Nonastrocytic Gliomas

Oligodendroglioma 133

Anaplastic Oligodendroglioma 134

Infratentorial Ependymoma 135

Subependymoma 136

Typical Choroid Plexus Papilloma 137

Neuronal and Mixed Neuronal-Glial Tumors

Ganglioglioma 138

Dysembryoplastic Neuroepithelial Tumor (DNET) 139

Central Neurocytoma 140

Pineal and Germ Cell Tumors

Pineocytoma 141

Pineal Parenchymal Tumor of Intermediate

 Differentiation (PPTID) 142

Germinoma 143

Miscellaneous Primary Tumors

Medulloblastoma 144

Hemangioblastoma 145

Primary CNS Lymphoma 146

Intravascular (Angiocentric) Lymphoma 147

Leukemia 148

Metastatic Tumors and Remote Effects of Cancer

Parenchymal Metastases 149

Miscellaneous Intracranial Metastases 150

Metastatic Intracranial Lymphoma 151

Paraneoplastic Syndromes and Limbic Encephalitis 152

Treatment-Related Effects

Radiation and Chemotherapy 153

Pseudoprogression (PsP) 154

Pseudoresponse 155

Primary Nonneoplastic Cysts

Primary Nonneoplastic Cysts Overview 156

Arachnoid Cyst 160

Colloid Cyst 161

Dermoid Cyst 162

Epidermoid Cyst 163

Hippocampal Sulcus Remnant Cysts 164

Enlarged Perivascular Spaces 165

Pineal Cyst 166

Choroid Plexus Cyst 167

Porencephalic Cyst 168

Infectious, Inflammatory, and

Demyelinating Disease

Infections

CNS Infectious Disease Overview 169

Meningitis 171

Abscess 172

Ventriculitis 173

Empyema 174

Herpes Encephalitis 175

HHV-6 Encephalitis 176

West Nile Virus Encephalitis 177

Miscellaneous Encephalitis 178

Cerebellitis 179

Tuberculosis 180

Neurocysticercosis 181

Lyme Disease 182

Acquired HIV Encephalitis 183

Acquired Toxoplasmosis 184

Acquired CMV 185

Fungal Infections 186

PART I: BRAIN

SECTION 2

Pathology-Based Diagnoses: Neoplasms,

Cysts, and Disorders