Inflammatory (xanthomatous) pseudotumors of the breast are very rare and this case is the first reported case in Korea. A healthy, pregnant 29-year-old woman presented with a right breast mass. Ultrasonography of the breast revealed a 1.8 x 1.9 x 1.1 cm, sized lobulated, partially spiculated mass in the upper and outer quadrant of the breast. Macroscopically, the mass was well circumscribed, bright yellow, and lobulated. Microscopically, the tumor was composed of foamy histiocytes with multifocal neutrophilic infiltration, accompanying chronic inflammatory cellul infiltration, fibrosis and ductal-lobular atrophy.