Pseudohypertension in a child with Williams syndrome.

Pseudohypertension has often been reported in elderly subjects, but is an unusual phenomenon in children. We report the case of a 5-year-old child who presented with features of Williams syndrome (characterized by elfin facies, supravalvar aortic stenosis, and peripheral pulmonary artery stenosis). Repeated blood pressure recordings made with appropriately sized blood pressure cuffs were very high, while simultaneous intraarterial blood pressure was normal, confirming the presence of pseudohypertension. This was shown to be caused by excessively thickened arterial vessels.