Dr. Roland G. Ware: A 41-year-old woman was admitted five years ago with pain and swelling in the left arm. A clot was surgically removed from the left subclavian vein. She was asymptomatic until six months before admission when she developed pain and swelling in the face and both upper extremities, at which time she was treated with chlorothiazide (Diuril). Two months before admission the swelling and pain in her face and upper trunk increased. She complained of dizziness, epistaxis, and headache. There were prominent veins in the extremities and upper thorax. She experienced no chills, fever, or weight loss. Physical examination revealed a pleasant, cooperative woman whose blood pressure was 125/80 mm Hg in both upper extremities. The pulse, temperature, and respirations were normal. Her face and upper extremities were plethoric and edematous. Her eyes were prominent and the conjunctiva injected. The veins of the face, neck, and upper