Objective To compare the clinical efficacy of intralesional corticosteroid injection combined with topical corticosteroids versus topical corticosteroids alone in patients with idiopathic granulomatous mastitis (IGM).

Methods Patients diagnosed with IGM and treated at the Breast Surgery Department of Peking Union Medical College Hospital between October 2016 and March 2018 were retrospectively analyzed. Based on treatment modalities, patients were divided into an injection group (receiving intralesional corticosteroid injections plus topical corticosteroids) and a control group (receiving topical corticosteroids alone). Clinical outcomes and recurrence rates were compared between the two groups.

Results Seventy-eight patients meeting the inclusion and exclusion criteria were enrolled, with 51 in the injection group and 27 in the control group. The median age was 35 years (range: 22-45). The maximum lesion diameter was 8.7±2.9 cm in the injection group and 7.1±2.7 cm in the control group. Compared with the control group, the injection group showed a significantly shorter time to half remission(2.8±0.9 weeks vs. 4.2±1.3 weeks, P < 0.001) and a shorter time to complete remission(8.8±2.5 weeks vs. 10.1±2.7 weeks, P=0.043). During a follow-up period of 74 months, recurrence occurred in 2 patients in the injection group (1 ipsilateral and 1 contralateral) and 1 patient in the control group (contralateral).

Conclusions Compared with topical corticosteroid monotherapy, the combina-tion of intralesional corticosteroid injection and topical corticosteroids provides faster symptom control and shorter treatment duration while maintaining high efficacy and low long-term recurrence rates, offering a more effective therapeutic option for IGM patients.