PIK3CA-related overgrowth spectrum
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A child has asymmetric overgrowth affecting one leg with vascular malformations and epidermal nevi. Tissue biopsy reveals a somatic PIK3CA variant.
Somatic (mosaic); PIK3CA
- Includes: CLOVES, Klippel-Trenaunay, megalencephaly-capillary malformation
- Segmental/asymmetric overgrowth
- Vascular malformations
- Epidermal nevi
- Variable features depending on timing and tissue distribution
- Recognize the clinical overgrowth pattern (segmental/asymmetric, vascular malformations, lipomatous overgrowth, megalencephaly)
- Confirm with sequencing of affected (lesional) tissue; the somatic PIK3CA variant is often undetectable in blood, so a biopsy of affected tissue with high-sensitivity (deep) sequencing is preferred
- Imaging to map extent of overgrowth and vascular malformations (MRI/MRV); echocardiography if megalencephaly-capillary malformation (cardiac involvement)
- Multidisciplinary care coordinated by overgrowth and vascular anomaly specialists
- Alpelisib (PI3K pathway inhibitor) for severe or refractory PIK3CA-related overgrowth
- Orthopedic management of limb-length discrepancy; interventional/surgical treatment of symptomatic vascular malformations; anticoagulation/thrombosis risk monitoring with extensive venous malformations
- Recurrence risk is low (postzygotic mosaicism); no increased risk to future offspring or siblings in most cases