Evaluating the impact of COVID-19 infection and vaccination on the presentation and severity of idiopathic granulomatous mastitis: A retrospective cohort study.

This study aimed to investigate the differences in the occurrence, clinical course, and severity of Idiopathic granulomatous mastitis (IGM) before and after the COVID-19 pandemic. Additionally, we evaluated the potential relationship between the COVID-19 vaccine and infection in individuals diagnosed with granulomatous mastitis during the pandemic. The files of patients who applied to our breast care center between October 2011 and October 2023 were scanned via an electronic data system, and patients with a pathologically confirmed diagnosis of IGM were identified. Among these patients, those over 18 years of age and without missing data were included in the study. Patients under the age of 18, those with incomplete data, and those with a positive tuberculosis polymerase chain reaction test were excluded from the study. Demographic data, application dates and complaints, breastfeeding history, ultrasonography findings, polymerase chain reaction tests for tuberculosis, treatment data, COVID-19 vaccination status, and infection histories were recorded. There were 183 female patients who met the inclusion criteria. The patients were divided into 2 groups; pre-COVID (n = 132, mean age 34.02 ± 5.75 years) and post-COVID (n = 51, mean age 34.23 ± 5.2 years). There was no significant difference between the groups for the pre and post-COVID periods in terms of demographic data, presenting symptoms and imaging findings, BI-RADS classification, or maximal lesion diameter on ultrasound (P ≥ .05). The proportion of vaccinated patients in the post-pandemic group was greater than that of unvaccinated patients. While a significantly higher proportion of post-COVID patients received steroid therapy, the surgical rate was significantly lower. Although there was no significant difference in the occurrence of IGM during the pandemic period, there was an increase in IGM in those who received the mRNA vaccine. These findings, suggested a potential association between mRNA vaccine and IGM. Further investigations to understand the underlying mechanisms are needed. In this period, conservative treatment has become prominent in the treatment of the disease.