Granulomatous lobular mastitis: two case reports with focus on radiologic and histopathologic features.

Granulomatous lobular mastitis (GLM) is a rare, benign condition with an unknown etiology that can appear as cancer on mammogram, ultrasound, and magnetic resonance imaging. The terminology of GLM was first named by Going et al (J Clin Pathol 1987;40:535-540) in 1987 after he noted the lobule centered distribution on histologic exam. We present 2 case reports of GLM that clinically and radiographically appeared as malignant lesions. The first case was a 31-year-old woman with a 1-month history of breast mass, and the second case was a 33-year-old woman with a 2-week history of breast mass. Both cases were histologically diagnosed as GLM. Retrospectively, we identified ultrasound and magnetic resonance imaging characteristics that may be used in the future to classify the breast mass before biopsy.