Sudden, unexpected infant death due to pulmonary arterial hypertension

A 3-year-old girl with no particular medical history complained of a stomachache and died on the way to the hospital. The autopsy revealed marked right ventricular hypertrophy and dilation with no other cardiac abnormalities. Microscopically, the pulmonary small arteries showed marked medial hypertrophy and varying degrees of intimal and adventitial thickening. We supposed that the cause of death was attributable to pulmonary arterial hypertension (PAH). PAH is a rare disease that can cause sudden, unexpected death at any age. Forensic pathologists should consider PAH in the differential diagnosis of sudden death.