||Friction trauma may produce a subperichondrial serous or serosanguineous effusion. A seroma will usually persist for several days after the original injury.
If the seroma fails to resolve spontaneously, aspiration may be necessary. If fluid reaccumulates, repeated aspiration or excision of the lining membrane is suggested. A long-standing seroma may organize into subepithelial thickening, particularly if the effusion was hemorrhagic.
This retarded child developed a seroma following several hours of vigorously rubbing his ear against a mattress. The pale bulge of the seroma is visible over the upper portion of the antihelix.