1 Department of Surgery, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
2 Breast Health & Cancer Research Center, Iran University of Medical Sciences, Tehran, Iran.
3 Orthopedic Research Center, School of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
4 Concordia University, Montreal, Canada.
5 Wake Forest Institute of Regenerative Medicine, Winston-Salem, NC, USA. Kiarash.Astani@Advocatehealth.org.

Purpose: Idiopathic granulomatous mastitis (IGM) is a chronic, relapsing inflammatory breast disease of unknown etiology. Its unpredictable course and unclear pathogenesis have made treatment a persistent clinical challenge. This study aimed to evaluate treatment outcomes in patients with IGM, focusing on extending remission periods and reducing relapse rates after discontinuation of therapy.

Methods: This retrospective cohort study included 200 patients with histopathological confirmed idiopathic granulomatous mastitis who were referred to the Teaching and Therapeutic Center at the Central Hospital of Mazandaran University of Medical Sciences. Patient demographics, pathological characteristics, treatment regimens, remission duration, and recurrence rates were analyzed.

Results: From January 2018 to December 2024, a total of 200 patients were enrolled in the study, with a mean age of 33 years (range: 18-54 years) and a mean follow-up duration of 34 months (range: 8-51 months). Patients were divided into two treatment groups: Group A received high-dose prednisolone combined with abscess drainage (n = 99), while Group B received low-dose prednisolone, abscess drainage, and methotrexate (n = 101). Group B demonstrated a significantly shorter treatment duration (11.56 ± 2.15 months) compared to Group A (14.86 ± 3.42 months; P < 0.001). The mean time to follow-up was significantly longer in Group B (35.97 ± 6.96 months) than in Group A (20.00 ± 7.02 months; P < 0.001). The recurrence rate was lower in Group B (4.9%) than in Group A (23.2%), with the difference approaching statistical significance (P = 0.057). In addition, the mean time to relapse in Group B (34.46 ± 6.50 months) was significantly longer than that of Group A (16.96 ± 5.34 months), indicating that patients receiving the combined regimen of low-dose prednisolone, drainage, and methotrexate experienced a more sustained remission period.

Conclusions: According to the results, the treatment of idiopathic granulomatous mastitis, especially the moderate to severe form of the disease, using combination therapy with low-dose prednisolone and methotrexate can be associated with a reduction in treatment duration, and increase in remission duration, and a reduction in relapse, and drug side effects.