Presentation
Antenatal anomaly ultrasound. No complaints. Gestational age: 26 weeks 3 days.
Patient Data
CUA - 25 weeks 4 day +/- 1 wk 0 day.
There is a well-defined hyperechoic mass lesion in posterior cranial fossa of the fetus. No internal cystic changes/calcification/vascularity is noted in the lesion. It is posterior to and abutting left cerebellar hemisphere. Cerebellar hemisphere itself shows normal echopattern. Lesion reaches up to midline. Vermix could not be separately seen. Cisterna magna is normal in size (6 mm). Lesion approximately measures 21 x 16 x 10 mm. There is no hydrocephalus. No skull vault defect.
No other abnormality was noted.
Affected cerebellar hemisphere is atrophic. No other abnormality was noted. 1st and 2nd images show affected hemisphere. Last image is not properly documented but shows normal size of unaffected hemisphere.
Case Discussion
The initial interpretation of the first ultrasound was a possible extra-axial lesion. Subsequent fetal MRI (not shown) demonstrated that there was a cerebellar parenchymal hemorrhage, cerebellar hemispheric atrophy was also reported.