Granulomatous mastitis: etiology, imaging, pathology, treatment, and clinical findings

To outline the demographics, clinical presentation, imaging features, and treatment modalities observed among a series of patients diagnosed with biopsy-proven granulomatous mastitis (GM).

Following approval by institutional review board, retrospective chart review was performed on patients with biopsy-proven granulomatous mastitis at our institution in the period from January 2013 until October 2017.

A total of 90 patients were identified: 87 women and 3 men. The mean age was 35 years, mostly women in their reproductive age. In our study, patients with GM were more likely to be Hispanic compared to the general population. Sixty-three percent of patients were within 5 years of previous pregnancy. Painful palpable mass-like lesion was the most common physical finding. Breast ultrasound (US) was performed in all patients, and most commonly showed a hypoechoic irregular-shaped mass. Mammography (MG) showed asymmetry or irregular mass as the main finding. Definitive diagnosis was obtained by imaging-guided core needle biopsies in 94.4%. Conservative management was preferred, and only one patient underwent surgery.

Although clinical and radiological findings of patients with GM may mimic those of breast carcinoma, our study showed that women of childbearing age, especially among Hispanic ethnicity with a recent history of pregnancy or high prolactin level and newly tender mass-like lesion, in addition to new focal asymmetry on mammogram and heterogeneous hypoechoic irregular-shaped mass on ultrasound exam, should raise concern for GM. Non-invasive approach and clinical follow-up were the preferred treatment method.