Cavernous malformations

Findings

CT shows multiple well circumscribed hyperdense lesions scattered throughout the brain parenchyma without any perilesional edema or extra-axial fluid collections. No mass effect.
MRI FLAIR images show mixed signal intensity of the “popcorn” lesions seen on CT. T1 images show increased signal consistent with blood products. GRE sequences show blooming of artifact and post contrast examination shows no enhancement.

Differential diagnosis for "Popcorn ball" lesion:
- Cavernous malformation
- AVM
- Hemorrhagic neoplasm
- Calcified neoplasm (oligodendroglioma)

Differential diagnosis for multiple black dots:
- Cavernous malformation
- Old trauma (contusions, DAI)
- Hypertensive petechial hemorrhage
- Amyloid angiopathy
- Capillary telangiectasis


Diagnosis: Cavernous malformations


Key points

Benign vascular hamartoma with masses of closely apposed immature blood vessels ("caverns"), intralesional hemorrhages, no neural tissue.
CM = most common angiographically "occult" vascular malformation, approximate prevalence 0.5%.
75% occur as solitary, sporadic lesion.
10-30% multiple, familial.

Zabramski classification of CMs:
- Type 1 = subacute hemorrhage (hyper intense on T1WI; hyper- or hypo intense on T2WI)
- Type 2 = mixed signal intensity on T1-, T2WI with degrading hemorrhage of various ages (classic "popcorn ball" lesion)
- Type 3 = chronic hemorrhage (hypo- to iso on T1-, T2WI)
- Type 4 = punctate micro hemorrhages ("black dots"), poorly seen except on GRE sequences

Most common signs/symptoms:
- Seizure 50%
- Neurologic deficit 25% (may be progressive)
- 20% asymptomatic