Ultrasound findings in the early diagnosis of idiopathic granulomatous mastitis: a large-scale study

Idiopathic granulomatous mastitis (IGM) is a benign but distressing chronic disease. Various etiologies have been proposed for this condition. Although histological examination is used for the definitive diagnosis of the disease, imaging methods including ultrasound (US) are important for achieving correct diagnosis, as well as assisting treatment in some cases. The aim of our study was to identify the most frequent and specific US findings for early IGM diagnosis in a large scale study. In this cross-sectional study, we extracted data from sonographic evaluations of 303 patients with early IGM at the time of their first presentation. These patients were referred to our clinic between June 2019 and August 2024. The mean age of the patients was 35.5 years. Among them, 46.4% of the patients were categorized as BI-RADS 4 and 30.4% as BI-RADS 3. Parenchymal edema was observed in 48.2% of the patients, and 66.7% had collections. US showed masses in 31.4% of the cases, with the majority of these being hypoechoic. Skin thickening was seen in 21.5% of the patients, and fistulae were present in 5%. Axillary lymphadenopathy was present in 50.2%, of which 61.9% showed cortical thickening. In our experience with IGM US, we found that the simultaneous presence of collections and parenchymal edema in 32.3% of the patients. May be useful for differentiating IGM from other breast lesions. US is a useful tool for evaluating the early phases of IGM. Our findings raise a suggestion that the simultaneous presence of collections and parenchymal edema at ultrasound may decrease the necessity for biopsy to obtain a definitive diagnosis of IGM, especially when considering other clinical symptoms. Further prospective studies with a validated design are necessary to test this hypothesis, along with comparison to other groups with benign and malignant breast masses.