case_images: PMC11735054_01
case_images: The cyst observed under the scalp of the fetus using two-dimensional ultrasonography and magnetic resonance imaging (MRI). (a) Image obtained using two-dimensional ultrasonography at 20 weeks of gestation. A 15 x 5 mm fetal scalp cyst and a vague border between the cyst and fetal skull bone can be seen. (b) Image obtained using two-dimensional ultrasonography with power Doppler at 22 weeks of gestation. No blood flow from the intracranial space to the scalp cyst could be observed; however, blood vessels were present. (c) Image of the lateral view obtained using T2-weighed MRI at 32 weeks of gestation. A border between the scalp cyst and fetal skull bone can be seen. (d) Image of the coronal view obtained using T2-weighed MRI at 32 weeks of gestation. A border between the scalp cyst and fetal skull bone can be seen.
case_images: CRINM2025-7401673.001.jpg
case_images: PMC11735054_01_CRINM2025-7401673.001.jpg
case_images: fig1
case_images: An ultrasonography examination revealed a single fetus with a 15 x 5 mm parietal cyst on the scalp that was not connected to the blood flow, and did not include the tissue of the brain parenchyma (Figures 1(a), 1(b)). Fetal MRI performed at 32 weeks and 4 days of gestation confirmed a fluid-filled mass 15-mm in diameter, and ruled out the connection to the intracranial space from the fetal scalp cyst (Figures 1(c), 1(d)).
case_images: Gross findings and postnatal magnetic resonance imaging (MRI) of the scalp cyst. (a) Lateral view of the scalp cyst (yellow arrow). (b) Frontal view of the scalp cyst. A small lesion is observed (yellow arrow). (c) Lateral view of the small scalp cyst connected to the intracranial space observed using T2-weighed MRI.
case_images: CRINM2025-7401673.002.jpg
case_images: PMC11735054_01_CRINM2025-7401673.002.jpg
case_images: fig2
case_images: Apgar scores at 1 and 5 min were 8 and 9, respectively. A small bump on the head of the neonate was observed during the gross examination, but no other remarkable abnormalities were detected (Figures 2(a), 2(b)). However, MRI on postnatal day 5 revealed a small connection between the intracranial space and scalp cyst, resulting in a diagnosis of a parietal MC (Figure 2(c)).
case_images: Images obtained during volume contrast imaging (VCI) of the head at 22 weeks of gestation and during postnatal computed tomography (CT). (a) The circular defect of the fetal skull bone, connecting to the sagittal suture in the right lower image, can be seen. (b) The posterior view of postnatal CT image showing the posterior fontanelle and skull bone defect of the neonate. (c) The parietal view of postnatal CT image showing the anterior fontanelle and skull bone defect of the neonate.
case_images: CRINM2025-7401673.003.jpg
case_images: PMC11735054_01_CRINM2025-7401673.003.jpg
case_images: fig3
case_images: Subsequently, we reanalyzed the prenatal ultrasonography data obtained at 22 weeks of gestation using VCI, which revealed the circular defect of the fetal skull bone connecting to the sagittal suture (Figure 3(a)). Computed tomography (CT) on postnatal day 34 revealed a bone defect on the parietal skull (Figures 3(b), 3(c)).