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Introduction Demographics Causes Clinical features Diagnosis Differential diagnoses Outcome
Megalencephaly-capillary malformation-polymicrogyria (MCAP) was first described in 1997 and is characterised by:
Additional features include varying degrees of asymmetric somatic overgrowth, distal limb malformations, and hyperelasticity. Fewer than 300 cases have been reported in the literature.
MCAP is also known as macrocephaly-capillary malformation (MCM), to reflect large brain size, large head size, and polymicrogyria that characterise the syndrome.
MCAP occurs sporadically and affects boys and girls equally with no ethnic predilections.
Some cases of MCAP have been found to have somatic mutations in the phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene on chromosome 3q26.
These major criteria must both be present for MCAP to be diagnosed:
Minor criteria: variable involvement
Diagnosis of MCAP is made based on clinical signs and neuro-imaging studies. Both major criteria should be present, with variable minor criteria.
Baseline magnetic resonance imaging (MRI) of the brain and spine is recommended at the time of diagnosis.
MCAP should be distinguished from other overgrowth syndromes with vascular malformations including:
Patients with MCAP require ongoing medical surveillance as well as physical and occupational therapy. Early intervention is helpful to overcome disability and achieve developmental milestones.
Patients are at increased risk of developing medulloblastoma, meningioma, Wilms tumour and leukaemia over their lifetime.
In addition to yearly medical exams, all patients should have cardiology consultation at the time of diagnosis.
Follow-up imaging recommendations include:
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