Observation Alone for Mild Non-Lactational Mastitis

Non-Lactational Granulomatous Lobular / Periductal Mastitis (NL-GLM/PDM) is an inflammatory breast disease of unclear etiology, primarily characterized by the presence of breast masses. A variety of treatment approaches, including intralesional injection, ductal lavage therapy, or corticosteroids had been proposed. Recently, an increasing number of studies have demonstrated that an observation and follow-up strategy for mild cases can yield comparable efficacy. An international consensus recommends that this observation strategy may serve as a first-line treatment approach for mild NL-GLM patients, with additional therapies implemented only upon disease progression.However, in clinical practice, we have observed that some patients with mild NL-GLM/PDM experience disease progression during the observation period, necessitating further treatment. The proportion of this population and the specifics of their disease progression remain unknown. Additionally, the clinical and pathological factors associated with disease progression during observation have not been previously studied. This research aims to conduct a single-center, single-arm, prospective cohort study to investigate the rate and timing of disease progression in mild NL-GLM/PDM during observation, as well as to explore the clinical and pathological factors related to progression. The findings will provide further guidance for subsequent research and clinical practice.

• Observation (Other): In this study, the definition of "observation" is that participants cannot receive the following treatments currently considered to have a clear efficacy for NL-GLM/PDM, including surgical treatments (minimally invasive excision or open excision, incision and drainage), ultrasound-guided aspiration, oral corticosteroid therapy, antibiotic treatment, anti-tuberculosis therapy, or ductal lavage therapy. As symptomatic management for pain, the use of NSAIDs is permitted. Additionally, for patients with fistulas or skin lesions, routine wound care is also allowed. These two interventions are not considered as receiving treatment intervention in this study.

Primary outcomes

• 12-weeks Progression Free Proportion [12 weeks after enrollment]: The proportion of patients who did not experience disease progression events within 12 weeks after enrollment.
• 12-weeks Treatment Free Proportion [12 weeks after enrollment]: The proportion of patients who did not experience any predefined treatments within 12 weeks after enrollment.

Secondary outcomes

• 4-weeks Progression Free Proportion [4 weeks after enrollment]: The proportion of patients who did not experience disease progression events within 4 weeks after enrollment.
• 24-weeks Progression Free Proportion [24 weeks after enrollment]: The proportion of patients who did not experience disease progression events within 24 weeks after enrollment.
• 4-weeks Treatment Free Proportion [4 weeks after enrollment]: The proportion of patients who did not experience predefined treatments within 4 weeks after enrollment.
• 24-weeks Treatment Free Proportion [24 weeks after enrollment]: The proportion of patients who did not experience predefined treatments within 24 weeks after enrollment.
• Median time to progression among Progressors [24 weeks after enrollment]: The median time of the first occurrence of a progression event among patients who experience disease progression.
• Median time to treatment intervention among patients with active treatment [24 weeks after enrollment]: The median time of the first occurrence of a treatment intervention event among patients who experience treatment intervention.

Other outcomes

• Correlation between blood test indicators with clinical outcomes [24 weeks after enrollment]: Explore the correlation between baseline and week 4 inflammatory blood test indicators and their dynamic changes with disease progression and treatment intervention.
• Correlation between clinicopathological biomarkers with clinical outcomes [24 weeks after enrollment]: Explore the correlation between clinical indicators, pathological indicators, and ultrasound indicators at baseline with disease progression and treatment intervention.

Sex: Female, ages: 18 Years to 65 Years

Inclusion Criteria:

1. Female, aged 18 to 65 years;
2. Clinically diagnosed with possible non-lactational (more than 6 months since stopping breastfeeding) granulomatous lobular mastitis or periductal mastitis.
3. Mscore ≤ 4 points;
4. Patients with ultrasound findings suggesting localized breast abscess formation must have undergone abscess drainage before enrollment;
5. After education, participants should have a strong willingness for observation and follow-up, and, after discussing with the primary physician, jointly decide to proceed with observation and follow-up;
6. Signed informed consent form.

Exclusion Criteria:

1. Patients with confirmed or suspected breast malignancy;
2. Patients with bilateral mastitis (including those with bilateral simultaneous onset and those with sequential onset of non-lactational granulomatous mastitis);
3. Pregnant patients who are currently in the gestation period;
4. Patients who have had non-lactational mastitis in the same breast within the past year and have undergone treatments such as surgery, oral corticosteroids (for more than 2 weeks), anti-tuberculosis treatment (for more than 2 weeks), or ductal lavage therapy.
5. Patients who received surgery, oral corticosteroids, or anti-tuberculosis treatment for the non-lactational mastitis of the ipsilateral breast within 2 weeks before enrollment.

• Results publication: Yuan QQ, Xiao SY, Farouk O, Du YT, Sheybani F, Tan QT, Akbulut S, Cetin K, Alikhassi A, Yaghan RJ, Durur-Subasi I, Altintoprak F, Eom TI, Alper F, Hasbahceci M, Martinez-Ramos D, Oztekin PS, Kwong A, Pluguez-Turull CW, Brownson KE, Chandanwale S, Habibi M, Lan LY, Zhou R, Zeng XT, Bai J, Bai JW, Chen QR, Chen X, Zha XM, Dai WJ, Dai ZJ, Feng QY, Gao QJ, Gao RF, Han BS, Hou JX, Hou W, Liao HY, Luo H, Liu ZR, Lu JH, Luo B, Ma XP, Qian J, Qin JY, Wei W, Wei G, Xu LY, Xue HC, Yang HW, Yang WG, Zhang CJ, Zhang F, Zhang GX, Zhang SK, Zhang SQ, Zhang YQ, Zhang YP, Zhang SC, Zhao DW, Zheng XM, Zheng LW, Xu GR, Zhou WB, Wu GS. Management of granulomatous lobular mastitis: an international multidisciplinary consensus (2021 edition). Mil Med Res. 2022 Apr 26;9(1):20. doi: 10.1186/s40779-022-00380-5. PMID 35473758