An observational study in Idiopathic Granulomatous Mastitis and Granulomatous Mastitis, sponsored by European Breast Cancer Research Association of Surgical Trialists. Recruiting at 2 sites in Germany. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-15.
Sponsored by European Breast Cancer Research Association of Surgical Trialists · Observational
Idiopathic granulomatous mastitis (IGM) is a rare benign inflammatory breast condition with unknown cause, affecting approximately 2.4 per 100,000 women aged 20-40 years. Patients experience severe local symptoms including pain, redness, and recurrent abscesses that can last weeks to months and often mimic inflammatory breast cancer. Due to its rarity, mostly case reports and case series exist in the literature, leading to limited knowledge about risk factors, optimal treatment strategies, and clinical outcomes.
The GRAMAREG study is the first European registry for patients with histologically confirmed idiopathic granulomatous mastitis. This retrospective/prospective observational cohort study aims to systematically evaluate the incidence, diagnostic features, clinical course, treatment strategies, and patient outcomes of this uncommon disease. The study collects both retrospective data (from January 1, 2015 onwards) and prospective data from participating sites across Europe.
All diagnostic and therapeutic procedures are conducted according to institutional standards in clinical routine, as this is a non-interventional study. Patients in the prospective cohort are followed for up to 5 years to document symptom duration and recurrence rates.
Background:
Idiopathic granulomatous mastitis was first described by Kessler and Wolloch in 1972. The etiology remains largely unknown due to its rare occurrence. Valid prevalence data in Europe are lacking, though incidence appears higher in low-income countries compared to Western Europe. IGM predominantly occurs in women of childbearing age, mostly parous and more frequently of non-white ethnicity.
The diagnosis is confirmed only by histological evaluation, typically using core needle biopsy. Patients commonly develop recurrent breast abscesses that do not improve with antibacterial medication and often require repeat incisions or drainages. IGM must be differentiated from granulomatous inflammation associated with duct ectasia, foreign material reactions, specific infections (tuberculosis, fungi, parasites), systemic granulomatous diseases (sarcoidosis), and cystic neutrophilic granulomatous mastitis (CNGM) linked to Corynebacterium species.
Treatment strategies described in literature include high-dose steroids, immunosuppressive agents, bromocriptine, antibiotics, surgical resection, or even mastectomy. However, no evidence-based treatment recommendations are currently available.
Study Design:
This is an investigator-initiated non-interventional observational international prospective/retrospective cohort study with unlimited accrual and open registry duration due to disease rarity.
Data Collection Methods:
Retrospective Phase:
Collection and analysis via anonymized electronic database maintained by EUBREAST e.V. Participating Study Sites identify and document patients with histologically confirmed IGM treated between January 1, 2015, and Study Site activation. No patient identifying information is disclosed or documented. Data are fully anonymous without prospective follow-up.
Prospective Phase:
Patients with histologically confirmed IGM presenting after Study Site activation are informed about possible participation. Written informed consent is obtained. Diagnostic management and treatment follow institutional standards without protocol deviation. Follow-up occurs at 1, 3, and 5 years after first diagnosis to evaluate current symptoms and document potential recurrence.
22 studies on the registry are indexed under Granulomatous Mastitis; 7 are open to participants now.
This study's planned enrollment of 1,000 is above the median of 79 across 10 observational studies indexed under Granulomatous Mastitis.
Browse Granulomatous Mastitis studies →European Breast Cancer Research Association of Surgical Trialists is the lead sponsor of 4 studies on the registry; 4 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Patients diagnosed with histologically confirmed idiopathic granulomatous mastitis (IGM) or cystic neutrophilic granulomatous mastitis (CNGM) at participating European breast centers and hospitals. The population includes both retrospectively identified patients (diagnosed January 1, 2015, through Study Site activation) and prospectively enrolled patients (diagnosed after Study Site activation). IGM predominantly affects women of childbearing age, mostly parous, and more frequently of non-white ethnicity, though both males and females ≥18 years are eligible.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Histologically or cytologically confirmed
The diagnosis was confirmed by looking at a sample under a microscope: tissue from a biopsy or surgery (histology), or cells from a fluid or needle sample (cytology).
Your pathology report is the document that shows this.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Biopsy and archival tissue
A biopsy takes a small piece of tissue to examine. “Archival tissue” is a sample already taken, for example at diagnosis, and kept by the hospital.
Whether a stored sample will do depends on when it was taken, how much there is and what the study needs. Ask whether the study accepts your stored sample or needs a new biopsy.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Female and male patients ≥18 years old with histologically confirmed idiopathic granulomatous mastitis (IGM) or cystic neutrophilic granulomatous mastitis (CNGM) diagnosed after January 1, 2015. Histological confirmation obtained by minimally invasive biopsy or on surgical specimen by local pathology. Excludes patients with secondary granulomatous mastitis due to tuberculosis, sarcoidosis, fungal and parasitic infection, or foreign body.
Proportion of Patients Presenting with Specific Symptoms
Percentage of patients presenting with specific clinical symptoms including pain, redness, and palpable breast mass at initial presentation
Time frame: At initial diagnosis (baseline)
Duration of Symptoms Depending on Treatment Strategy
Time from initial symptom onset to symptom resolution measured in weeks or months, stratified by treatment approach (systemic treatment, surgical intervention, conservative management)
Time frame: From initial diagnosis through symptom resolution, up to 5 years
Type and Duration of Systemic Treatment
Specific systemic treatments received (e.g., corticosteroids, immunosuppressive agents, antibiotics) and duration of each treatment in weeks or months
Time frame: From initial diagnosis through completion of treatment, up to 5 years
Number of Surgeries Performed
Total number of surgical procedures (incision, drainage, excision, mastectomy) required per patient
Time frame: From initial diagnosis through 5 years follow-up
Recurrence Rate
Proportion of patients experiencing recurrence of idiopathic granulomatous mastitis after initial treatment
Time frame: At 1, 3, and 5 years after first diagnosis
Risk Factors Associated with Recurrence
Identification of patient demographics, clinical characteristics, and treatment factors associated with disease recurrence
Time frame: At 1, 3, and 5 years follow-up
Time to Histological Confirmation
Time interval in days or weeks between first symptom occurrence and first histological confirmation of idiopathic granulomatous mastitis
Time frame: At baseline (from retrospective chart review or patient recall)
Presentation on Breast Imaging
Imaging characteristics on mammography, sonography, and MRI (if performed) as assessed by the International Steering Committee
Time frame: At initial diagnosis
Started Jul 2026 (actual). Primary completion is estimated for Apr 2031, 57 months after the start.
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European Breast Cancer Research Association of Surgical Trialists