A 45-year-old man presented with a 3-year history of a painless, soft, and slow-growing swelling of the neck, upper trunk, upper back, and shoulders (Panels A and B). The patient had a history of heavy alcohol consumption and was a nonsmoker. Laboratory blood analysis showed minor elevations in aspartate aminotransferase (71 U per liter), alanine aminotransferase (49 U per liter), and total cholesterol (235 mg per deciliter [6.08 mmol per liter]). Triglycerides were very elevated at 1020 mg per deciliter (11.52 mmol per liter). Magnetic resonance imaging revealed diffuse, nonencapsulated fatty deposits in the mediastinum and in the subcutaneous and . . .