MRI cross section of the brain
ASNR

CAse of the week

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ASNR Case of the Week: Case 125

Hx: developmental delay and hemifacial macrosomia.

MRI cross section of a brain of a young femail patient with developmental delay and hemifacial macrosomia

Answer

Megalencephaly-Capillary Malformation-Polymicrogyria Syndrom (MCAP)

  • Mechanism: Somatic mutation in PI3K-AKT related genes lead to disruption of cell signaling in vascular, limb, and brain development.
  • Clinical Presentation: Variable but may include prenatal overgrowth, cutaneous vascular malformations, digital anomalies, connective tissue abnormalities, and brain and body asymmetry.
  • Imaging
    • Intracranial findings may include ventriculomegaly, hemimegalencephaly, hydrocephalus, polymicrogyria, cerebella tonsil ectopia, thickening of the corpus callosum, myelination abnormalities, septum pellucidum variants.
    • Extracranial findings include fatty overgrowth ipsilateral to hemimegalencephaly, limb hypertrophy with leg lenght discrepancy, syndactyly, and vascular malformations.
  • Treatment- Approved therapies involve targeting the PI3K mutation (Alpelisib)
  • Differential Diagnosis:
    • Dyke-Davidoff-Masson syndrom, Sturge Weber syndrome
  • Article Reference link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5177701/
  • Case was confirmed with genetic testing for PIK3CA mutation
MRI reveals chiari type 1 malformation (a), hemimegalencephaly with enlargement of the left hemisphere and lateral ventricle with subtle asymmetric cortical thickening in the left perisylvian cortex (b), and enlargement of the left subcutaneous and parapharyngeal fat planes with fatty infiltration of the left pterygoid muscles (c).