What are the new findings with regard to the mysterious disease idiopathic granulomatous mastitis?

Treatment modalities for granulomatous mastitis, seeking the most appropriate treatment with the least recurrence rate: a systematic review and meta-analysis

BACKGROUND

Granulomatous mastitis (GM) is a rare, benign, inflammatory breast disease with an unknown etiology that predominantly affects women of reproductive age. The definitive treatment of GM is currently controversial; an appropriate therapeutic strategy has yet to be identified, and the disease's high recurrence rate remains. This study aims to determine the recurrence rate for each GM treatment strategy to identify the most appropriate treatment modality.

METHODS

The search for relevant articles was undertaken using three international databases, including Medline, Scopus, and Web of Science. Articles published in English until the end of 2021 evaluating the recurrence rate of GM were included. Using Stata 13.0, the pooled incidence and 95% confidence interval (CI) for the recurrence rate were determined.

RESULTS

Sixty-five eligible studies were included in our study. The recurrence rates of systemic steroid use, topical steroid use, antibiotic use, methotrexate use, observation, drainage, excision, antibiotic use and surgery, steroid use and surgery, antibiotic and steroid use, methotrexate and steroid use were 24% (95% CI: 21-27%), 11% (95% CI: 6-21%), 18% (95% CI: 14-22%), 13% (95% CI: 7-22%), 11% (95% CI: 7-17%), 65% (95% CI: 50-78%), 13% (95% CI: 10-16%), 23% (95% CI: 14-36%), 7% (95% CI: 5-11%), 11% (95% CI: 6-18%), and 4% (95% CI: 2-8%), respectively. Drainage had the highest recurrence rate, while combined methotrexate and steroid treatment had the lowest rate.

CONCLUSION

The optimal treatment strategy for GM depends on the disease's severity, consequences, and the patient's features. The study results indicate that combination therapy is preferable for minimizing the risk of relapse and reducing treatment complications.

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.

Factors Affecting Recurrence of Idiopathic Granulomatous Mastitis: A Systematic Review

Idiopathic granulomatous mastitis is a rare and benign disease that primarily affects young women of reproductive age. Various factors have been suggested as possible causes, including pregnancy, breastfeeding, history of taking birth control pills, hyperprolactinemia, smoking, and history of trauma. Due to unknown etiology, opinions on its treatment have varied, resulting in differing recurrence rates and side effects. Therefore, conducting a comprehensive systematic review and meta-analysis can aid in understanding the causes and recurrence of the disease, thereby assisting in the selection of effective treatment and improving the quality of life. A systematic literature review was conducted using predefined search terms to identify eligible studies related to risk factors and recurrence up to June 2022 from electronic databases. Data were extracted and subjected to meta-analysis when applicable. A total of 71 studies with 4735 patients were included. The mean age of the patients was 34.98 years, and the average mass size was 4.64 cm. About 3749 of these patients (79.17%) were Caucasian. Patients who mentioned a history of pregnancy were 92.65% with 76.57%, 22.7%, and 19.7% having a history of breastfeeding, taking contraceptive pills, and high prolactin levels, respectively. Around 5.6% of patients had previous trauma. The overall recurrence rate was 17.18%, with recurrence rates for treatments as follows: surgery (22.5%), immunosuppressive treatment (14.7%), combined treatment (14.9%), antibiotic treatment (6.74%), and observation (9.4%). Only antibiotic and expectant treatments had significant differences in recurrence rates compared to other treatments (p value = 0.023). In conclusion, factors such as Caucasian race, pregnancy and breastfeeding history, and use of contraceptive hormone are commonly associated with the disease recurrence. Treatment should be tailored based on symptom severity and patient preference, with surgery or immunosuppressive options for recurrence.

Differential expression profiles of miRNA in granulomatous lobular mastitis and identification of possible biomarkers

The etiology and pathogenesis of granulomatous lobular mastitis (GLM) remain largely elusive and the expression levels and regulatory roles of microRNAs (miRNAs or miRs) in GLM have remained mostly undetermined. In the present study, the miRNAs that were differentially expressed in breast biopsy samples from patients with GLM and normal tissue adjacent to fibroadenoma were analyzed, a comprehensive differential expression profile of miRNAs was provided and potential biomarkers were screened out. The expression profile of miRNAs was determined by high-throughput sequencing in the tissues of patients with GLM and healthy controls. Significantly differentially expressed miRNAs were screened by threshold setting and cluster analysis and their target genes were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Finally, circulating differentially expressed miRNAs between the GLM and control groups were further analyzed by reverse transcription-quantitative PCR (RT-qPCR). A total of 31,077 miRNAs were detected by high-throughput sequencing. By using the cutoff criteria of |log2 fold change|>2.5 and q<0.001, 13 miRNAs that were indicated to be GLM biomarkers were screened out. The expression levels of these 13 miRNAs in the GLM group were higher than those in the control group. GO and KEGG enrichment analyses suggested that the occurrence and development of GLM may be associated with autoimmune inflammation, metabolism and pathogenic organisms. miR-451a and miR-5571-3p were confirmed to be significantly increased in the serum of patients with GLM compared with their levels in the serum of healthy volunteers, which suggests that they may be used as biomarkers of GLM. To the best of our knowledge, the present study was the first report detailing genome-wide miRNA profiling of patients with GLM compared with controls. The possible targets and pathways of GLM were evaluated by bioinformatics analysis. The present study identified 13 differentially expressed miRNAs with important theoretical significance and potential application. Furthermore, miR-451a and miR-5571-3p were verified by RT-qPCR as possible biomarkers of GLM.

Granulomatous mastitis associated with erythema nodosum: A case series of 42 patients

BACKGROUND

Granulomatous mastitis (GM) is defined by the formation of granulomatous inflammation in breast tissue. Erythema nodosum (EN) is a reactive inflammatory panniculitis characterized by erythematous subcutaneous nodules in the lower limbs. The association of GM with EN has been rarely reported. Our aim was to retrospectively review our series of patients with GM to better characterize their features and their association with EN.

METHODS

Cases histologically diagnosed as granulomatous inflammation in breast tissue between 1995 and 2020 were retrospectively reviewed.

RESULTS

Forty-two women were diagnosed with GM. The average age at diagnosis was 41.619years, and 59.5% were of South-American ethnicity. EN was associated with GM in 11.9% of the patients. Patients with EN were diagnosed earlier than isolated GM (0.4months vs 6.81months; P<.05). Ulceration in the GM was more prevalent in patients with associated EN (60% vs 14.7%; P<.05).

CONCLUSION

EN in patients with GM may reduce the evolution time and may help to diagnose this rare condition that mimics breast carcinoma.