Eosinophilic Mastitis: A Case Report

Eosinophilic mastitis is a rare disease in which eosinophils infiltrate the ducts and lobules of the breast, causing mammary inflammation. Although eosinophilic mastitis is a benign condition, it presents similarly to and is often mistaken for breast cancer. Here we report the first case of eosinophilic mastitis in Korea. A 43-year-old woman presented with redness and swelling in her right breast. A breast ultrasound revealed ill-defined isoechoic and hyperechoic areas in the upper half and lower inner quadrant of the right breast combined with axillary level I lymphadenopathy. A histopathological examination by core needle biopsy demonstrated lymphoplasma cell infiltration with eosinophils. A peripheral blood examination revealed an eosinophil count of 5,000/mm3. The patient was treated with oral steroids, antibiotics, and leukotriene receptor antagonists. Four months later, the eosinophil count had returned to normal, and breast ultrasound exhibited marked improvement.