A breast clinical scoring system to identify women with Idiopathic granulomatous Mastitis

Idiopathic granulomatous mastitis (IGM) is a benign inflammatory breast condition that can resemble mastitis or malignancy clinically and radiographically. We aimed to develop a quantitative scoring system, based off the Komen Inflammatory Breast Cancer (IBC) scoring system [1], evaluating clinical and radiologic features to distinguish IGM from benign and malignant breast conditions.

We conducted a retrospective chart review of biopsy-proven IGM patients diagnosed from 2014 to 2025 via institutional electronic medical records. Clinical symptom onset, features, and diagnostic imaging were analyzed. A continuous scoring scale (1-50) was created, encompassing three categories: symptom onset, clinical features, and radiographic findings. Scores of IGM patients were compared with those of patients diagnosed with IBC, mastitis (lactational and non-lactational), and locally advanced breast cancer (LABC). Welch's two-sample t-test assessed statistical differences, and Youden index identified the optimal score threshold for predicting IGM.

Among 148 IGM patients, predominantly Hispanic (56.8%) and Asian (26.7%), the mean age was 37.2 years, older than mastitis patients and younger than IBC patients. Key clinical features included pain or painful breast mass (100%), fistula or draining wound (77.7%), erythema (94.6%), and phlegmon (87.8%). Imaging revealed mass with collection in 84.6% and multiple masses/collections in 38.9%. The mean IGM score (35.5) was significantly higher than scores for IBC, mastitis, and LABC groups (14.4, 18, and 15.2, respectively; p ≤ 0.05). A score ≥ 24.5 predicted IGM with 93% sensitivity and 95% specificity.

This novel scoring system provides an objective framework to differentiate IGM from similar breast conditions, facilitating early diagnosis and guiding appropriate management.

not applicable.