Development of Choroid Plexus

• Choroid plexus development starts between 6–7 weeks post-conception (p/c).
• Initial formation occurs in the fourth ventricle.
• Later becomes most prominent in the lateral ventricles.
• Achieves adult anatomical configuration by ~20 weeks gestation.

Formation Process:

• Begins as neuroepithelial projections into ventricular cavities.
• These projections form choroidal villi.
• Small cysts/tubules can develop within these villi due to neuroepithelial tissue folding and separation.

Choroid Plexus Cysts (CPC)

Overview:

• Common fetal ultrasound finding, usually benign.
• Typically identified in the second trimester.
• Prevalence: Found in up to 1% of pregnancies.

Clinical Characteristics:

• Usually diagnosed between 16–24 weeks gestation.
• Size typically <10 mm.
• Majority spontaneously resolve by 24 weeks gestation.

Clinical Significance:

• Isolated CPCs (no associated anomalies):
  • No increased risk for developmental or neurological impairment.
  • No significant long-term clinical implications.
• Association with chromosomal anomalies:
  • Frequently seen in trisomy 18 (up to 50% of cases).
  • Rarely associated with trisomy 21.
• Congenital infections:
  • Bilateral CPCs may rarely indicate congenital infections (e.g., CMV), especially if associated with subependymal germinolysis.

Prognosis and Management:

• Generally excellent if isolated; no specific intervention needed.
• Follow-up ultrasound recommended to confirm resolution.
• Counseling regarding chromosome screening if additional markers or abnormalities present.

Choroid Plexus Papillomas

Definition:

• Rare benign tumors arising from choroid plexus epithelium.
• Typically found within lateral ventricles of fetus.

Clinical Presentation:

• Usually presents with fetal hydrocephalus:
  • Due to excessive cerebrospinal fluid (CSF) production.
  • Potential obstruction of ventricular outflow foramina.

Imaging and Diagnosis:

• Identified on prenatal ultrasound or fetal MRI.
• Requires postnatal imaging confirmation and neurosurgical evaluation.

Prognosis and Management:

• Management usually involves surgical resection after birth.
• Prognosis favorable if timely intervention provided; complications primarily due to hydrocephalus.

Key Differential Points:

Clinical Recommendations:

• Isolated CPC: reassure parents, limited/no follow-up required.
• Associated CPC findings (e.g., additional ultrasound anomalies):
  • Consider chromosome analysis.
  • Evaluate maternal infection status (CMV testing if indicated).
• Choroid Plexus Papilloma: Refer for multidisciplinary prenatal and postnatal neurosurgical planning.