A 35-year-old woman was admitted to the intensive care unit with progressive shortness of breath. She had been diagnosed during childhood as having Klippel-Trenaunay-Weber syndrome. This diagnosis was based on asymmetrical enlargement of her right leg, combined vascular malformations, and varicosities. On admission, the physical examination showed a gigantic hemihypertrophy of her right leg. The circumference of her right thigh exceeded that of her left by approximately a factor of 3. A CT scan revealed an immense thickening of the subcutaneous soft tissue, increased inter- muscular fat layer, and lymphedema. Extensive varicosities of superficial and deep veins were present (Figure 1, arrows). The femoral artery and its branches were massively dilated. The chest CT scan showed an immense dilatation of the pulmonary trunk as well as the main pulmonary arteries (Figure 2, arrows). As a result of a chronic increase in the cardiac index, severe pulmonary hypertension had developed. Right heart catheterization revealed a pulmonary arterial pressure of 80/40 mm Hg (mean pressure 56 mm Hg). The patient died from a high-output cardiac failure.