A single-arm, proof-of-concept trial has shown the safety and efficacy of ductal lavage as a treatment for idiopathic granulomatous mastitis patients (Manuscript accepted in Journal of Surgical Research 2018). In this multicenter, randomized, open-labeled, non-inferior trial, the investigators are going to enroll eligible granulomatous mastitis patients and randomized them into ductal lavage versus. corticosteroids therapy group. The primary endpoint of this study is the complete clinical response rate at 1 year after the enrollment. The aim of this study is to provide evidence for the management of idiopathic granulomatous mastitis patients .

Non-lactational mastitis (NLM) consists of a broad spectrum of inflammatory breast diseases. Among them, periductal mastitis and idiopathic granulomatous mastitis(IGM) are the most commonly encountered in clinical practice. IGM can be diagnosed when all possible causes of granulomatous diseases (known mycobacterial or fungal infection, Wegener granulomatosis, sarcoidosis, etc.) are excluded. There is no consensus on the standard treatment of IGM patients. Surgery, oral corticosteroids, topical steroids, immunosuppressive therapy, and observation alone were all proposed as the treatment for IGM patients. However, all of the evidences are derived from retrospective studies. In a previous study, the investigators conducted a single-arm, proof-of-concept trial that showed the safety and efficacy of ductal lavage as a treatment for IGM patients. Ductal lavage is possible to spare the patients from corticosteroids therapy and or surgery. To further address this issue, the investigators are going to conduct this multicenter, randomized, open-labeled, non-inferior trial, to compare the efficacy and safety of ductal lavage and corticosteroids therapy. The aim of this study is to provide evidence for the management of IGM patients.

Inclusion Criteria:

• Female, age between 18 and 65 years old.
• Inform consent signed.
• Clinical diagnosis of non-lactating mastitis, defined as mastitis occurred more than 1 month after the cessation of lactation.
• Clinical and pathological diagnosis of idiopathic granulomatous mastitis.
• Never receive surgical treatments, or corticosteroids therapy after the cessation of lactation. Core needle biopsy is allowed.
• Good health, judged by clinicians, to receive ductal lavage.
• M score >=2

Exclusion Criteria:

• Grade III inverted nipple(Plastic. Reconstruction. Surgery. 104: 389, 1999.)
• Lactational mastitis patients.
• Bilateral IGM patients.
• Clinically diagnosis of periductal mastitis.
• Pathological diagnosis of breast carcinoma.
• Pregnant women.
• Evidences suggest possible diagnosis of SLE(systemic lupus erythematosus), rheumatic disorders or other systematic auto-immune diseases.
• Evidences suggest possible diagnosis of tuberculosis.
• Evidences suggest possible diagnosis of fungus infection of the breast
• History of breast trauma.
• History of taking oral corticosteroids or anti-tuberculosis treatment.
• Imaging examinations indicates foreign objects retained in the breast
• Presence of sepsis or severe inflammation caused by IGM, for which surgery is likely required.
• Patients with inappropriate coagulation function, cardiac function, pulmonary function, liver and renal function, that clinicians judges as not suitable to participate in this study.

The study protocol and the raw and clean data for analysis will be shared among the participated researchers. Non-researchers could obtain relevant informations from the researchers upon reasonable requests.