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Missouri Derm

Case of the Month

Presented by: Abby Rosenberg, PGY-4

Program: Washington University in St. Louis

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Patient Presentation

Patient was a former 39-week large-for-gestational age male
Presented at birth with left-sided hemihypertrophy, diffuse reticulate capillary malformations on the trunk and extremities, discrete capillary malformations on the lower lip and lower back, and hemangioma-like lesions on the left thigh and right shoulder
Brain MRI was notable for left-sided megalencephaly and minimal frontotemporal polymicrogyria.
Additional abnormal findings included a cerebellar tonsillar herniation known as Chiari I defect and a rare portosystemic shunt known as Abernathy Malformation

Skin biopsy and diagnosis

Skin biopsy revealed a pathogenic p.E81K mutation in PIK3CA
Patient was diagnosed with Megalencephaly Capillary Malformation Syndrome (MCAP), a disease on the PIK3CA Related Overgrowth Spectrum (PROS)
At age 11 months, patient developed disseminated intravascular coagulation in the setting of an upper respiratory illness, highlighting the known association between MCAP and hypercoagulability

Treatment

He remained on sirolimus until age 5 when it was discontinued during an acute illness
One month after discontinuation → he showed no evidence of progression

If his condition does progress, the plan is to start alpelisib, a medication which was recently FDA-approved for some patients with life-threatening complications of PROS disorders

Conclusion

This case highlights some of the common clinical findings in MCAP including the risk of hypercoagulable complications, making it essential to anticoagulate these patients prior to any surgeries
In addition, this case underscores the beneficial role of sirolimus in PROS disorders

What is the mechanism of action of sirolimus?

What is the mechanism of alpelisib?