Idiopathic Granulomatous Lobular Mastitis: A Case Report.

Introduction: Idiopathic granulomatous mastitis (IGM), also known as nonpuerperal mastitis or granulomatous lobular mastitis, is a rare, benign, chronic inflammatory breast disease first characterized in 1972. IGM is characterized by sterile noncaseating lobulocentric granulomatous inflammation, usually affecting parous premenopausal women with a history of lactation.

Case presentation: We present a 38-year-old African American woman presenting to our continuity clinic complaining of a painful right breast mass discovered during a self-breast examination. An initial right breast ultrasound demonstrated an area of concern with asymmetry, architectural distortion, and a questionable mass correlating to a 5.1 cm hypoechoic mass at the 12:30 position. Additionally, a mammogram showed a suspicious, indeterminate, large hypoechoic region or mass with angular margins measuring 5.1 x 1.7 x 3.7 cm with slight internal vascularity. An ultrasound-guided stereotactic biopsy revealed extensive mixed inflammatory and focal granulomatous lobular mastitis.

Conclusion: Idiopathic granulomatous mastitis is a rare disorder that often mimics breast malignancies and infectious processes. This case highlights the need for further research on IGM pathogenesis to prevent unnecessary life-altering therapeutic procedures and bring awareness to the medical community.