Observation Alone for Mild Non-Lactational Mastitis: A Cohort Study.

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.