Aetiology of idiopathic granulomatous mastitis

Breastfeeding and secretory factors in idiopathic granulomatous mastitis: Unveiling etiological insights

BACKGROUND

Idiopathic granulomatous mastitis (IGM) is a rare, chronic inflammatory, and benign breast disease. Its unclear etiology may involve autoimmune reactions, secretion-related factors, and microorganisms.

AIM

To analyze data from our IGM patient series and compare potential etiological factors.

METHODS

We prospectively collected data using follow-up forms for patients diagnosed with IGM at our breast clinic from September 2014 to December 2020 and analyzed it retrospectively.

RESULTS

The study cohort included 220 patients, with a median age of 34 years (range: 20-58). A majority, 217 patients (98.6%), reported a history of breastfeeding, with a median duration of 36 months (range: 0-156). The median interval between the last breastfeeding session and disease onset was 25 (25th-75th percentiles: 15-44) months. Additionally, 116 patients (53.5%) reported breastfeeding-related problems. In 41 surgical patients, dense milky-brown debris in the breast ducts was noted. Although no independent seasonal fluctuations in disease onset were detected, a reduction in IGM cases during the summer months was found to correlate with a general decrease in all breast clinic visits.

CONCLUSION

Most patients reported recent breastfeeding and half experienced related problems, supporting the secretion theory's relevance in IGM's etiology. The absence of seasonal fluctuations suggests that secretion-related factors may be more central to IGM development than autoimmunity or infections. These findings offer crucial insights for future research into IGM's complex causes.

Concurrence of idiopathic granulomatous mastitis and breast cancer in a patient on neoadjuvant chemotherapy: A case report

INTRODUCTION

Idiopathic Granulomatous Mastitis is a rare benign inflammatory disease of the breast.

PRESENTATION OF THE CASE

We present a case of 45-year-old woman who was diagnosed with stage II invasive ductal carcinoma in the left breast. While receiving neoadjuvant chemotherapy, she developed idiopathic granulomatous mastitis (IGM) in the left breast after the second cycle. She underwent modified radical mastectomy and has been managed with steroids for IGM on the contralateral side, which developed later in the course of the disease. This is a unique finding with limited literature available on similar cases, to the best of our knowledge.

DISCUSSION

IGM poses a diagnostic challenge requiring histopathology for definitive diagnosis.

CONCLUSION

Treatment guidelines of IGM are not established making it difficult to manage.

Comparing the Efficacy of Intralesional Injection versus Systemic Steroids in Treating Idiopathic Granulomatous Mastitis: Insights from a Single-Center Experience

Objective

Idiopathic granulomatous mastitis (IGM) is a benign inflammatory condition predominantly affecting women of reproductive age, particularly those with a history of breastfeeding. Although the precise etiology remains unknown, treatment strategies continue to be a subject of debate. This study aimed to compare the efficacy of intralesional steroid (ILS) injections with oral steroid (OS) therapy in managing IGM.

Materials and Methods

A total of 72 patients, clinically and histopathologically diagnosed with IGM, were treated with either ILSs (group ILS, n = 47) or OSs (group OS, n = 25) at a tertiary referral hospital between January 2022 and January 2024. The data were retrospectively analyzed.

Results

The mean age of the patients was 33.5 years (range: 22-56). No statistically significant differences were observed between the two groups in terms of demographic characteristics, presenting symptoms, clinical findings, or laboratory results. The mean treatment duration was 6 months. There were no significant differences in treatment response or recurrence rates between the two groups. However, there was a statistically significant difference in the incidence of side effects, with 6.3% in the ILS group compared to 36% in the OS group (p = 0.001).

Conclusion

Given its ease of application, lower incidence of side effects, and comparable efficacy, ILS injections may be considered a first-line treatment option in the management of IGM.

Granulomatous mastitis forming a well-defined large mass diagnosed by surgical excision: a case report

BACKGROUND

Granulomatous mastitis is a relatively rare benign inflammatory disease of the breast, but it is sometimes difficult to distinguish from breast cancer by imaging. We experienced a case that was definitively diagnosed as granulomatous mastitis from the surgical specimen. The mass appeared as a large cystic lesion on imaging, which is unusual for granulomatous mastitis, and was initially suspected to be an encapsulated papillary carcinoma.

CASE PRESENTATION

A 43-year-old woman presented with a painful mass in her right breast. Ultrasonography revealed a cystic mass lesion with internal solid components, with partially indistinct cyst walls and abundant blood flow. Additionally, lymphadenopathy of one axillary lymph node was observed. Magnetic resonance imaging findings showed irregularly spreading enhanced nodules within the cystic lesion, raising the suspicion of encapsulated papillary carcinoma. Although the histological findings from a needle biopsy were consistent with granulomatous mastitis, the possibility of malignancy could not be ruled out based on imaging, prompting a diagnostic probe lumpectomy. However, the surgical specimens did not reveal any tumorous lesions, and we reached a final diagnosis of granulomatous mastitis. Postoperatively, the patient was followed-up without steroid therapy and has been free from recurrence of mastitis for 22 months after surgery.

CONCLUSIONS

We report a case of granulomatous mastitis that was detected as a large cystic lesion with a well-defined border on imaging and a definitive diagnosis was made from a surgical specimen.

>Efficacy of disease-modifying antirheumatic drugs in the treatment of granulomatous mastitis: a systematic review

INTRODUCTION

Idiopathic granulomatous mastitis (IGM) is an inflammatory breast disorder of unknown etiology. This benign condition can mimic the clinical presentation of breast cancer and is characterized by symptoms such as breast pain, erythema, and swelling. Over the past few years, Disease-Modifying Antirheumatic Drugs (DMARDs) have been increasingly used to manage this condition. However, strong evidence to support their use is lacking.

OBJECTIVES

This systematic review aimed to summarize the evidence and evaluate the efficacy of DMARDs in the management of IGM.

METHODS

A systematic literature review, adhering to PRISMA guidelines, was conducted across electronic databases, including PubMed, EMBASE, SCOPUS, directory of open access journals (DOAJ) and Cochrane Library from their inception until May 2024. We included retrospective and prospective studies while excluding case reports and case series of less than 10 patients.

RESULTS

Eighteen studies met our eligibility criteria. Fifteen studies were retrospective, while 2 were prospective. No randomized controlled trials were identified. Of these, 16 papers examined the effect of methotrexate on IGM, revealing significant disease improvement in most cases. Several of the studies indicated that patients treated with azathioprine and mycophenolate mofetil also achieved favorable responses.

CONCLUSION

Given the rarity of IGM, only a limited number of studies have explored the use of DMARDs as a pharmacological treatment option. A significant barrier to advancing our understanding is the substantial heterogeneity in the quality and volume of data provided by these studies. Therefore, there is a need for well-designed, randomized, placebo-controlled trials to rigorously assess the efficacy of DMARDs in the treatment of IGM.

Corynebacterium parakroppenstedtii secretes a novel glycolipid to promote the development of granulomatous lobular mastitis

Granulomatous lobular mastitis (GLM) is a chronic idiopathic granulomatous mastitis of the mammary gland characterized by significant pain and a high propensity for recurrence, the incidence rate has gradually increased, and has become a serious breast disease that should not be ignored. GLM is highly suspected relative to microbial infections, especially those of Corynebacterium species; however, the mechanisms involved are unclear, and prevention and treatment are difficult. In this study, we demonstrated the pathogenicity of Corynebacterium parakroppenstedtii in GLM using Koch's postulates. Based on the drug sensitization results of C. parakroppenstedtii, and utilizing a retrospective study in conjunction with a comprehensive literature review, we suggested an efficacious, targeted antibiotic treatment strategy for GLM. Subsequently, we identified the pathogenic factor as a new type of glycolipid (named corynekropbactins) secreted by C. parakroppenstedtii. Corynekropbactins may chelate iron, cause the death of mammary cells and other mammary -gland-colonizing bacteria, and increase the levels of inflammatory cytokines. We further analyzed the prevalence of C. parakroppenstedtii infection in patients with GLM. Finally, we suggested that the lipophilicity of C. parakroppenstedtii may be associated with its infection route and proposed a possible model for the development of GLM. This research holds significant implications for the clinical diagnosis and therapeutic management of GLM, offering new insights into targeted treatment approaches.

Current approaches to diagnosing and treating idiopathic granulomatous mastitis: A summary from in-depth clinician interviews

Background

Idiopathic granulomatous mastitis (IGM) is a rare, chronic inflammatory breast condition primarily affecting women of reproductive age. Its diagnosis is challenging due to similarities with other breast disorders, necessitating exclusion of other granulomatous diseases. The management of IGM remains inconsistent and unclear, with high recurrence rates and varying practices.

Methods

This qualitative study involved semi-structured interviews with nine clinicians from Singapore, Malaysia, and Egypt to examine current diagnostic and therapeutic approaches for IGM. Transcripts were analysed using NVivo software for coding and summarisation.

Findings

Clinicians predominantly used imaging and histopathology for diagnosis. Treatment commonly involved corticosteroids, though dosages and tapering regimens varied widely. Methotrexate was used sparingly for refractory cases due to associated risks. Surgical interventions were infrequent, reflecting a preference for medical management. There was a consensus on the need for randomised controlled trials (RCTs) to establish standardised treatment protocols.

Interpretation

This study reveals the complex nature of IGM diagnosis and treatment from clinicians in Singapore, Malaysia and Egypt. This underscores the need for more specific and definitive diagnostic tests, rather than relying on exclusionary methods, and standardised treatment guidelines. Multi-centre RCTs are essential for developing evidence-based protocols to improve patient outcomes and address regional differences effectively.

The First Reported Case of Hafnia alvei Granulomatous Mastitis in Humans

Granulomatous mastitis (GM) is an uncommon, chronic inflammatory breast disease, mostly idiopathic. Occasionally, the causative organism is isolated. It is characterized histologically by polymorph nuclear neutrophils' predominance and the absence of caseous necrosis. Idiopathic GM could be associated with other general conditions like autoimmune disorders, diabetes mellitus, and sarcoidosis. We report a case of a 41-year-old woman who presented with a left breast abscess of two weeks duration and a three-year history of intermittent attacks of painful breast swelling, which required multiple and extended empirical courses of antibiotics. Diagnosis as GM caused by Hafnia alvei bacteria was only confirmed by biopsy of the inflammatory mass and culture of the pus. The course of treatment was over three years, with three relapses.

Would hyperbaric oxygen therapy be a supportive treatment method for refractory idiopathic granulomatous mastitis?

BACKGROUND

Refractory IGM causes patients to use antibiotics, steroid therapy, immunosuppressive agents for a very long time and even leads to surgical procedures resulting in the loss of breast tissue. Hyperbaric Oxygen Therapy (HBOT) is a frequently used method in the treatment of wounds that are difficult to heal. We thought that HBOT would be an alternative treatment method for refractory IGM patients.

METHODS

It is a retrospective cohort study on refractory IGM patients conducted at three tertiary care treatment centers between January 2021 and July 2023. The patients were evaluated in two groups: those who only took steroid treatment and those who received HBOT and steroid treatment. The demographic and clinical characteristics of the patients, the types of treatment applied and their responses to treatment were evaluated.

RESULTS

There were no significant differences generally in the demographic and clinical features in both groups. The incidence of multicentric GM was found to be higher in the HBOT group (66.67 %; p = 0.044). Although the recovery results were similar in both groups, the average daily steroid dose and duration of drug use were found to be higher in the group receiving only steroid treatment (16 mg vs. 4 mg and 270 days vs. 30 days) (p < 0.001).

CONCLUSION

In our study, we showed for the first time in the literature that HBOT is effective in the treatment of refractory IGM patients. Our study needs to be supported by prospective studies evaluating cost effectiveness and possible long term complications.

Diagnosis, Approach, and Clinical Classification of Idiopathic Granulomatous Mastitis: Consensus Report

Objective

The aim of the idiopathic granulomatous mastitis (IGM) consensus study was to evaluate the etiology, diagnostic steps, and differential diagnosis and propose a widely accepted clinical classification of this mysterious breast disease.

Method

The organization of a national IGM consensus was decided by the joint evaluation of the Turkish Federation of Breast Diseases Societies, SENATURK, and the Society of Breast Surgery. First, a working group of 11 members was formed, and a survey and workshop were organized to reach a common consensus. The modified Delphi method was used in the consensus methodology. Voting rates of 80% and above were considered as acceptance.

Results

The consensus was 45/50 (92%) that core needle biopsies are necessary for the diagnosis of IGM and 39/40 (97%) that a new clinical classification is needed. The proposed Turkish clinical classification of IGM was accepted by 94% in three rounds of voting.

Conclusion

This disease should be considered etiologically idiopathic. Tissue diagnosis and pathological evaluation are recommended for treatment. The proposed IGM Turkey classification was strongly accepted.

Cornus Officinalis Total Glycosides Alleviate Granulomatous Lobular Mastitis via the B7-CD28/CTLA-4 Costimulatory Pathway

Cornus officinalis total glycosides (COTG) derived from the traditional Chinese medicine Cornus officinalis, is a natural immunosuppressant and has been extensively studied in immunomodulation and immunosuppression. This study aimed to explore the effects of COTG on granulomatous lobular mastitis (GLM) and its associated mechanisms. Compared to the model group, COTG effectively ameliorated histopathological damage to breast tissue, reduced mammary gland suppuration, and enhanced the blood-milk barrier. Additionally, COTG treatment reduced the total number of T cells and B cells in GLM rats, significantly improving clinical indicators such as P-selectin, E-selectin, and intercellular cell adhesion molecule-1. We also observed downregulation of CD28 and B7 expression levels, an upregulation of cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) expression, and a significant decrease in inflammatory marker levels in the COTG group. COTG exerts an anti-inflammatory effect in GLM by stimulating CTLA-4, inhibiting the B7-CD28 signaling pathway affecting T cell activation, and promoting the blood-milk barrier. These findings suggest that COTG could be a promising therapeutic option for managing GLM, potentially improving patient outcomes by modulating immune responses and reinforcing the blood-milk barrier.

Is poor oral health a risk factor for idiopathic granulomatous mastitis?

Idiopathic granulomatous mastitis (IGM) is a rare inflammatory breast disease that can be clinically and radiologically mistaken for carcinoma. Although its etiology remains uncertain, potential associations with pregnancy, lactation, hormonal imbalances, autoimmunity, smoking, and various microorganisms have been suggested. This study aimed to evaluate the relationship between IGM and oral health. We included 42 female patients diagnosed with IGM based on histopathological evaluations conducted between September 2018 and October 2023. The reference group consisted of 47 female patients with clinically, radiologically, and laboratory-proven non-specific mastitis and 36 healthy female individuals. The oral health of all participants was evaluated by an experienced dentist using the "Decayed, Missing and Filled Teeth" (DMFT) index and the "Simplified Oral Hygiene Index" (OHI-S). The ages of IGM patients included in this study ranged from 29 to 51 years, with a mean age of 34.88 ± 4.87 years. The most common clinical findings were pain (n = 38), palpable breast mass, erythema, induration, and dermal sinus. Comparison of the OHI-S and DMFT index values among participants revealed that those diagnosed with IGM had significantly higher values than those in the reference group (P < 0.05). Our findings suggest a potential involvement of poor oral health in the etiology of IGM. Future studies should consider oral health as a factor in IGM etiology and explore the oral microbiota in samples obtained from the affected tissue.

Genomic Insights into Idiopathic Granulomatous Mastitis through Whole-Exome Sequencing: A Case Report of Eight Patients

Idiopathic granulomatous mastitis (IGM) is a rare condition characterised by chronic inflammation and granuloma formation in the breast. The aetiology of IGM is unclear. By focusing on the protein-coding regions of the genome, where most disease-related mutations often occur, whole-exome sequencing (WES) is a powerful approach for investigating rare and complex conditions, like IGM. We report WES results on paired blood and tissue samples from eight IGM patients. Samples were processed using standard genomic protocols. Somatic variants were called with two analytical pipelines: nf-core/sarek with Strelka2 and GATK4 with Mutect2. Our WES study of eight patients did not find evidence supporting a clear genetic component. The discrepancies between variant calling algorithms, along with the considerable genetic heterogeneity observed amongst the eight IGM cases, indicate that common genetic drivers are not readily identifiable. With only three genes, CHIT1, CEP170, and CTR9, recurrently altering in multiple cases, the genetic basis of IGM remains uncertain. The absence of validation for somatic variants by Sanger sequencing raises further questions about the role of genetic mutations in the disease. Other potential contributors to the disease should be explored.

Idiopathic Granulomatous Lobular Mastitis: A Case Report

Introduction

Idiopathic granulomatous mastitis (IGM), also known as nonpuerperal mastitis or granulomatous lobular mastitis, is a rare, benign, chronic inflammatory breast disease first characterized in 1972. IGM is characterized by sterile noncaseating lobulocentric granulomatous inflammation, usually affecting parous premenopausal women with a history of lactation.

Case Presentation

We present a 38-year-old African American woman presenting to our continuity clinic complaining of a painful right breast mass discovered during a self-breast examination. An initial right breast ultrasound demonstrated an area of concern with asymmetry, architectural distortion, and a questionable mass correlating to a 5.1 cm hypoechoic mass at the 12:30 position. Additionally, a mammogram showed a suspicious, indeterminate, large hypoechoic region or mass with angular margins measuring 5.1 x 1.7 x 3.7 cm with slight internal vascularity. An ultrasound-guided stereotactic biopsy revealed extensive mixed inflammatory and focal granulomatous lobular mastitis.

Conclusion

Idiopathic granulomatous mastitis is a rare disorder that often mimics breast malignancies and infectious processes. This case highlights the need for further research on IGM pathogenesis to prevent unnecessary life-altering therapeutic procedures and bring awareness to the medical community.

The role of tissue IgG4 levels in steroid therapy in patients with idiopathic granulomatous mastitis

Idiopathic granulomatous mastitis (IGM) is a benign, chronic inflammatory lesion of the breast. Immunoglobulin G4 (IgG4) associated disease is rare in the breast. In our study, we aimed to evaluate the efficacy of steroid treatment on IgG4 levels in tissue in patients diagnosed with IGM. Between 2008 and 2017, 55 patients diagnosed with IGM in our clinic were included in the study. Demographic, clinical, microbiologic and histopathologic characteristics, treatment modality and recovery time were evaluated retrospectively. Patients were divided into 3 groups according to tissue IgG4 levels: negative (Group I), infrequently and slightly positive (Group II), and highly positive (Group III). Group I patients had a complete response rate of 77.8%. In the rest of the patients (22.2%), insufficient response was detected from the beginning of the treatment. In Group II, the response rate was 91.3% and the permanent success rate after treatment was 87.0%. Although group III patients had a complete response at the beginning (95.65%), they relapsed in a short period of time (26.1%) after discontinuation of steroid treatment. At least one steroid-related side effect was observed in 47 (85.8%) patients in all groups. There is no consensus on the dose and duration of immunosuppressive treatment in IGM. In this study, responses to steroid treatment according to IgG4 concentration in pathologic breast tissue and recurrences after the end of treatment were determined. We think that high IgG4 concentration in the tissue is associated with recurrence and other immunosuppressive drugs should be added as maintenance after steroid treatment.

Idiopathic Granulomatous Mastitis, Erythema Nodosum, and Polyarthritis

Idiopathic granulomatous mastitis (IGM) is an inflammatory-mediated rare disease that can be linked to rare manifestations. Erythema nodosum (EN) and polyarthritis, seen in a multitude of autoinflammatory and autoimmune diseases, have been rarely linked to IGM. Despite the cause of IGM being unclear, Corynebacterium infections are thought to play a role in the pathophysiology of IGM. Unusually, IGM has a relapsing and remitting course, which also applies to its systemic manifestations. As such, we present a case of IGM in a middle-aged lady who was initially thought to have Corynebacterium-containing unilateral abscesses for which drainage was performed. However, several abscesses devoid of bacterial growth started recurring, and the disease course was complicated by EN and polyarthritis. IGM, EN, and polyarthritis eventually resolved and were managed with symptomatic treatment.

Rare and Complicated Granulomatous Lobular Mastitis (2000-2023): A Bibliometrics Study and Visualization Analysis

Purpose

Granulomatous mastitis (GLM) is a rare and complex chronic inflammatory disease of the breast with an unknown cause and a tendency to recur. As medical science advances, the cause, treatment strategies, and comprehensive management of GLM have increasingly attracted widespread attention. The aim of this study is to assess the development trends and research focal points in the GLM field over the past 24 years using bibliometric analysis.

Methods

Using GLM, Granulomatous mastitis (GM), Idiopathic granulomatous lobular mastitis (IGLM), and Idiopathic granulomatous mastitis (IGM) as keywords, we retrieved publications related to GLM from 2000 to 2023 from the Web of Science, excluding articles irrelevant to this study. Citespace and VOSviewer were employed for data analysis and visualization.

Results

A total of 347 publications were included in this analysis. Over the past 24 years, the number of publications has steadily increased, with Turkey being the leading contributor in terms of publications and citations. The University of Health Sciences, Istanbul University, and Istanbul University Cerrahpasa were the most influential institutions. The Breast Journal, Breast Care, and Journal of Investigative Surgery were the journals that published the most on this topic. The research primarily focused on the cause, differential diagnosis, treatment, and comprehensive management of GLM. Issues related to recurrence, hyperprolactinemia, and Corynebacterium emerged as current research hotspots.

Conclusion

Our bibliometric study outlines the historical development of the GLM field and identifies recent research focuses and trends, which may aid researchers in identifying research hotspots and directions, thereby advancing the study of GLM.

Refractory and Recurrent Idiopathic Granulomatous Mastitis Treatment: Adaptive, Randomized Clinical Trial

BACKGROUND

Idiopathic granulomatous mastitis (IGM) is mostly described as an autoimmune disease with higher prevalence among Middle Eastern childbearing-age women. This study aimed to evaluate the best treatment of choice in patients with resistant or recurrent IGM.

STUDY DESIGN

Patients with established recurrent or resistant IGM who were referred to the Breast Cancer Research Center from 2017 to 2020 were randomly assigned to either one of the following treatment groups: A (best supportive care), B (corticosteroids: prednisolone), and C (methotrexate and low-dose corticosteroids). This adaptive clinical trial evaluated radiological and clinical responses, as well as the potential side effects, on a regular basis in each group, with patients followed up for a minimum of 2 years.

RESULTS

A total of 318 participants, with a mean age of 33.52 ± 6.77 years, were divided into groups A (10 patients), B (78 patients), and C (230 patients). In group A, no therapeutic response was observed; group B exhibited a mixed response, with 14.1% experiencing complete or partial responses, 7.7% maintaining stability, and 78.2% experiencing disease progression. Accordingly, groups A and B were terminated due to inadequate response. In group C, 94.3% achieved complete response, 3% showed partial remission, and 2.7% had no response to therapy. Among the entire patient cohort, 11.6% tested positive for antinuclear antibodies, 3.5% for angiotensin-converting enzyme, and 12.3% for erythema nodosum. Notably, hypothyroidism was a prevalent condition among the patients, affecting 7.2% of the cohort. The incidence of common side effects was consistent across all groups.

CONCLUSIONS

The most effective treatment option for patients with recurrent or resistant IGM is a combination therapy involving steroids and disease-modifying antirheumatic drugs such as methotrexate.

Imiquimod as a new treatment in refractory idiopathic granulomatous mastitis: report of two cases

INTRODUCTION

Idiopathic granulomatous mastitis (IGM) is a rare chronic inflammatory lesion of the breast that mimics breast cancer or infection. Immunological pathogenesis is strongly suggested for the disease.

REASON FOR THE REPORT

The treatment remains controversial, comprising a spectrum from observation or NSAIDs to immunosuppressive agents and surgery. Intractable cases are not uncommon and represent a major treatment challenge. Therefore in this study, we examine the effect of a topical immunomodulator agent, imiquimod, on refractory IGM. Patient 1 had IGM for 9 months and had not responded to the existing treatments. She responded to a 7-week course of imiquimod. In patient 2, the disease had begun 4 months sooner and had been resistant to all treatments; it responded to imiquimod after 4 weeks. Ulcers appeared on the skin of both patients but resolved safely.

OUTCOME

Both patients were very satisfied with the results. Imiquimod can be an appropriate local treatment with limited adverse effects in refractory IGM. We propose similar studies to assess the efficacy of imiquimod in IGM further, paying attention to the possibility of developing skin wounds.

A meta-analysis of idiopathic granulomatous mastitis treatments for remission and recurrence prevention

Purpose

The major aim of our meta-analysis was to review the effectiveness of various treatment modalities for achieving successful remission and preventing recurrence for women with idiopathic granulomatous mastitis (IGM). This knowledge is instrumental in developing evidence-based guidelines for clinicians to improve management strategies and outcomes for patients with IGM.

Methods

A systematic literature search was performed on MEDLINE (Ovid), Embase (Elsevier), PubMed, Cochrane Library, Web of Science, and Google Scholar; studies published to 19 January 2022 were included. A meta-analysis of 57 observational studies was performed. The results of two randomized controlled trials were also examined.

Results

There were 3,035 IGM patients across the observational and randomised studies. Overall recurrence and remission rates across all treatment strategies in 59 studies are 87.9% (2,667/3035) and 13.5% (359/2667), respectively. The studies reported 19 different treatment strategies, comprising observation, medical monotherapies, surgery, and combinations involving medical therapies, with and without surgery. Among monotherapy treatment, surgical management had the highest pooled remission rate (0.99 [95% confidence interval (CI) = 0.97-1.00]); among combination therapy, this was steroids and surgery (0.99 [0.94-1.00]). Antibiotic monotherapy had the lowest remission rate (0.72 [0.37-0.96]). The highest recurrence rates belonged to treatments that combined antibiotics and surgery (0.54 [0.02-1.00]), and antibiotics, steroids, and surgery (0.57 [0.00-1.00]). Most successful for preventing recurrence were observation (0.03 [0.00-0.10]), methotrexate (0.08 [0.00-0.24]), and steroids and surgery (0.05 [0.01-0.12]). There is a significant association between longer follow-up duration and recurrence rate reported, p = 0.002.

Conclusion

Combination therapies, especially those incorporating antibiotics, steroids, and surgery, have demonstrated higher remission rates, challenging the use of antibiotic monotherapy. There is an increased emphasis on the need for personalised, multi-pronged approach for preventing IGM recurrence, with longer follow-up care. More prospective future work in IGM research, with standardised diagnostic criteria, treatment protocols, and reporting guidelines will be important for developing treatment protocols and guidelines clinicians can adhere to in the clinical management of IGM patients.Systematic review registration: PROSPERO (CRD42022301386).

Clinical features and risk factors of bilateral granulomatous lobular mastitis

Granulomatous lobular mastitis (GLM) is an idiopathic inflammatory breast disease that tends to recur on the same side. With the accumulation of clinical cases, it has been observed that GLM can also occur contralaterally. Currently, most studies on GLM focus on treatment methods and risk factors for ipsilateral recurrence, and there are few reports on bilateral GLM. The study aimed to summarize the clinical characteristics of patients with bilateral GLM by reviewing their clinical data, and to discuss the risk factors affecting the occurrence of bilateral GLM. A retrospective study of the medical records database of patients with GLM admitted between May 2019 and August 2022 was performed. Patients were divided into bilateral GLM group (bilateral GLM group) and unilateral GLM patients (unilateral GLM group). Demographic and clinical characteristics, treatment, and follow-up were collected and analyzed. In this study, by reviewing the clinical data of 59 cases of bilateral GLM, we found that the median time between the onset of bilateral GLM on both sides was 6.63 (0-18) months. Additionally, because of the simultaneous or interval onset on both sides, the duration of the disease was longer compared to unilateral cases. Regarding the history of external hospital treatment, it was found that about 57.63% of patients with bilateral GLM received 2 or more treatment modalities, with a higher involvement of herbal medicine. Meanwhile, by counting the clinical data of the 2 groups of patients with bilateral GLM and unilateral GLM, it was shown by univariate analysis that fertility, nipple development, absolute CD4 value, and CD4/CD8 ratio were associated with contralateral onset of GLM in both groups, with inverted nipple being an independent risk factor.

Invasive Breast Cancer of No Special Type With Osteoclast-Like Giant Cells: A Cytological Clue Providing the Final Diagnosis for Histology

Breast cancer associated with osteoclast-like giant cells (OGCs) refers to a morphological pattern of invasive breast carcinoma of non-special type. Their presence is sometimes subtle, but OGCs can be appreciated both histologically and immunohistochemically. The origin of OGCs as well as their implication for prognosis remain debated. We describe the case of a 65-year-old woman, wherein the presence of OGCs in the fine-needle aspiration cytology of a metastatic axillary lymph node suggested the final diagnosis on histology. The differential diagnosis is broad, and here we provide evidence for strict cytological-histological correlation when dealing with unusual breast lesions.

Granulomatous mastitis in accessory breast tissue: A rare presentation and surgical management

Granulomatous mastitis (GM) in accessory breast tissue is rare. The present study aimed to report a rare case of GM in accessory breast tissue. A 39-year-old female patient presented with right axillary discomfort and swelling for ~5 days. On clinical examination, a tender, firm lump was detected in the right axillary region. The ultrasound showed diffuse parenchymal heterogeneity and surrounding edema in the right accessory breast associated with reactive axillary lymph nodes. Following unresponsiveness to conservative treatment, a surgical procedure was performed in the form of an excisional biopsy and the lesion was diagnosed as GM. During the six-month follow-up, there were no recurrences. The exact cause of GM remains uncertain and the etiology within accessory breast tissue is even less understood. Proposed mechanisms suggest that it may result from an exaggerated immune response triggered by various factors, such as infection, autoimmunity or hormonal fluctuations. GM in accessory breast tissue is a rare and challenging clinical condition to be diagnosed. Due to the rarity of this condition, it highlights the importance of including GM in the differential diagnosis of axillary masses.

Immune pathogenesis of idiopathic granulomatous mastitis: from etiology toward therapeutic approaches

Idiopathic granulomatous mastitis (IGM) is a noncancerous, chronic inflammatory disorder of breast with unknown causes, posing significant challenges to the quality of life due to its high refractoriness and local aggressiveness. The typical symptoms of this disease involve skin redness, a firm and tender breast mass and mastalgia; others may include swelling, fistula, abscess (often without fever), nipple retraction, and peau d'orange appearance. IGM often mimics breast abscesses or malignancies, particularly inflammatory breast cancer, and is characterized by absent standardized treatment options, inconsistent patient response and unknown mechanism. Definite diagnosis of this disease relies on core needle biopsy and histopathological examination. The prevailing etiological theory suggests that IGM is an autoimmune disease, as some patients respond well to steroid treatment. Additionally, the presence of concurrent erythema nodosum or other autoimmune conditions supports the autoimmune nature of the disease. Based on current knowledge, this review aims to elucidate the autoimmune-favored features of IGM and explore its potential etiologies. Furthermore, we discuss the immune-mediated pathogenesis of IGM using existing research and propose immunotherapeutic strategies for managing this condition.

The Effect of Local Steroid Administration on Idiopathic Granulomatous Mastitis: A Systematic Review andMeta-Analysis

INTRODUCTION

Idiopathic granulomatous mastitis (IGM) is a rare, benign inflammatory breast disease. Corticosteroids and surgery are the primary treatment options, and a growing number of publications have shown the effectiveness of local steroid administration (intralesional injection and topical corticosteroids). However, less is known about the specific details and effects of this treatment approach. The purpose of this meta-analysis was to summarize the details and evaluate the efficacy of local steroid administration for IGM.

METHODS

The PubMed, Embase, Cochrane Library, and SinoMed databases were systematically searched from inception to July 2023 to identify relevant randomized controlled trials. The quality of the included studies was assessed, and meta-analysis and subgroup analysis were conducted to obtain the pooled effect sizes of the outcomes of interest.

RESULTS

Eight trials comprising 613 patients were included. Local steroid administration included intralesional injection and topical steroid ointment, and control groups were mainly given systemic therapy (oral steroid) and surgical treatment. The meta-analysis showed that local steroid administration had a significant effect on the response rate (risk ratio [RR] = 1.35, 95% CI = [1.14-1.59], P = 0.0004). The incidence of side effects was also lower than that of systemic treatment (RR = 0.24, 95% CI = [0.13-0.43], P＜0.0001). There was no difference in the recurrence rate (RR = 0.8, 95% CI = [1.42-1.51], P = 0.48).

CONCLUSIONS

Local steroid administration can increase the RR and decrease the incidence of side effects for IGM patients. There is no significant difference in the recurrence rate between the local steroid administration group and the control group. Further studies are needed to identify the effect in different stages and among pregnant women.

Clinical Characteristics of Idiopathic Granulomatous Mastitis in a Hispanic Border Population: A Case Series and Literature Review

Idiopathic granulomatous mastitis (IGM) is an autoimmune condition of the breast that is commonly encountered in women of non-white ethnicity such as Southeast Asians, Middle Easterners, and Hispanics. This condition often presents as a painful breast mass, and many patients undergo invasive diagnostic procedures or surgical excision, which can lead to disfiguring scars. Early recognition and prompt treatment with immunosuppressive medications can prevent invasive workups and management. Although previously thought to require an exclusively surgical approach, it now prompts interdisciplinary management. In this context, we present a case series of patients with IGM in a Hispanic population of South Texas.

Pathological manifestations of granulomatous lobular mastitis

Granulomatous lobular mastitis (GLM) is a rare inflammatory breast disease with unknown etiology, characterized by non-caseous granulomatous inflammation of the lobules, which infiltrate lymphocytes, neutrophils, plasma cells, monocytes, and eosinophils may accompany. GLM is often misdiagnosed as breast cancer due to the lack of specificity in clinical and imaging examinations, and therefore histopathology is the main basis for confirming the diagnosis. This review provides an overview of the pathological features of granulomatous lobular mastitis and cystic neutrophil granulomatous mastitis (CNGM, a pathologic subtype of GLM). As well as pathologic manifestations of other breast diseases that need to be differentiated from granulomatous lobular mastitis such as breast tuberculosis, lymphocytic mastopathy/diabetic mastopathy, IgG4-related sclerosing mastitis (IgG4-RSM), nodular disease, Wegener's granulomatosis, and plasma cell mastitis. Besides, discusses GLM and CNGM, GLM and breast cancer, emphasizing that their relationship deserves further in-depth exploration. The pathogenesis of GLM has not yet been clearly articulated and needs to be further explored, pathology enables direct observation of the microscopic manifestations of the disease and contributes to further investigation of the pathogenesis.