Cystic neutrophilic granulomatous mastitis: an update

Cystic neutrophilic granulomatous mastitis: sensitivity and specificity of 16s rRNA and Sanger sequencing for Corynebacterium spp

AIMS

Cystic neutrophilic granulomatous mastitis (CNGM) is a subtype of granulomatous mastitis (GM) associated with Corynebacterium spp infection. We aimed to analyse the prevalence of Corynebacteria in CNGM and non-CNGM cases.

METHODS

Breast specimens diagnosed as granulomatous inflammation between 2010 and 2020 were reviewed to identify a CNGM cohort and a non-CNGM cohort. Polymerase chain reaction-based identification of Corynebacteria by 16S ribosomal RNA (16S rRNA) primers, followed by confirmatory Sanger sequencing (SS), was performed on all cases. Clinical, radiological and microbiology data were retrieved from the electronic patient records.

RESULTS

Twenty-eight CNGM cases and 19 non-CNGM cases were identified. Compared with the non-CNGM cohort, patients in the CNGM cohort were more likely to be multiparous (p=0.01), breast feeding (p=0.01) and presenting with a larger breast mass (p<0.01), spontaneous drainage (p=0.05) and skin irritation (p<0.01). No significant difference in the prevalence of Corynebacteria between the cohorts (7% vs 11%, p=0.68) by microbiological culture was identified. Compared with microbiology culture, the sensitivity and specificity of each Corynebacterial detection method were 50% and 81% for Gram stain, and 25% and 100% for 16S rRNA combined with SS. Regardless of the diagnosis, patients positive for Corynebacteria were more likely to have a persistent disease (p<0.01).

CONCLUSION

CNGM presents as a large symptomatic breast mass in multiparous breastfeeding women. The importance of adequate sampling and repeated microbiology culture in conjunction with sequencing on all GM cases with persistent disease is paramount.

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.

Idiopathic Granulomatous Mastitis

Idiopathic granulomatous mastitis (IGM) is a rare, benign inflammatory disorder of the breast that is often underrecognized. The exact etiology and pathophysiology are unknown, but milk stasis is felt to play a role. Classically, this condition is noninfectious, but many cases are noted to be associated with Corynebacterium species. Most patients affected are parous women with a mean age of 35, and many have breastfed within five years of diagnosis. Patients typically present with a painful mass and symptoms of inflammation, and these features can sometimes mimic breast cancer. Biopsy is needed to make a definitive diagnosis, and noncaseating granulomas are found on core biopsy. Many patients have a waxing and waning course over a period of six months to two years. Goal of treatment is to avoid surgery given poor wound healing, high risk of recurrence, and poor cosmetic outcomes. Medical treatment is preferred and includes observation, antibiotics, steroids, and immune modulators such as methotrexate. In more recent years, topical and intralesional steroids have become the treatment of choice, with similar outcomes to oral steroids.

Granulomatous mastitis in a 50-year-old male: A case report and review of literature

BACKGROUND

Granulomatous mastitis (GM) an inflammatory disease of the breast that usually affects women of childbearing age, occurs very rarely in males.

CASE SUMMARY

We present a case study of a 50-year-old male patient with GM. The patient developed a breast lump following the cleaning of a previously embedded dirt-filled nipple. While an initial improvement was noted with antibiotic therapy, a recurrence occurred a year later, showing resistance to the previously effective antibiotics. Subsequently, the lesion was excised. The histopathological examination confirmed the diagnosis of GM.

CONCLUSION

GM should be considered a possible diagnosis of male breast masses.

False-Positive and False-Negative Contrast-enhanced Mammograms: Pitfalls and Strategies to Improve Cancer Detection

Contrast-enhanced mammography (CEM) is a relatively new breast imaging modality that uses intravenous contrast material to increase detection of breast cancer. CEM combines the structural information of conventional mammography with the functional information of tumor neovascularity. Initial studies have demonstrated that CEM and MRI perform with similar accuracies, with CEM having a slightly higher specificity (fewer false positives), although larger studies are needed. There are various reasons for false positives and false negatives at CEM. False positives at CEM can be caused by benign lesions with vascularity, including benign tumors, infection or inflammation, benign lesions in the skin, and imaging artifacts. False negatives at CEM can be attributed to incomplete or inadequate visualization of lesions, marked background parenchymal enhancement (BPE) obscuring cancer, lack of lesion contrast enhancement due to technical issues or less-vascular cancers, artifacts, and errors of lesion perception or characterization. When possible, real-time interpretation of CEM studies is ideal. If additional views are necessary, they may be obtained while contrast material is still in the breast parenchyma. Until recently, a limitation of CEM was the lack of CEM-guided biopsy capability. However, in 2020, the U.S. Food and Drug Administration cleared two devices to support CEM-guided biopsy using a stereotactic biopsy technique. The authors review various causes of false-positive and false-negative contrast-enhanced mammograms and discuss strategies to reduce these diagnostic errors to improve cancer detection while mitigating unnecessary additional imaging and procedures. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Inflammatory Lesions of the Breast

CONTEXT.—

Inflammatory lesions of the breast are rare but not infrequently pose problems both clinically and morphologically, particularly on needle core biopsies. These lesions range from acute inflammatory conditions to chronic lymphoplasmacytic and lymphohistiocytic to granulomatous inflammatory diseases.

OBJECTIVE.—

To provide a comprehensive overview of inflammatory lesions of the breast, with etiopathogenesis and clinical, radiologic, and pathologic features as well as differential diagnostic considerations, clinical management, and prognosis.

DATA SOURCES.—

The existing literature in the English language, including original research articles and review articles describing inflammatory lesions of the breast.

CONCLUSIONS.—

Inflammatory lesions of the breast are characterized by a wide variety of clinical, radiologic, and morphologic features. The histopathologic differential diagnosis often includes a neoplastic process requiring ancillary studies and correlation with clinical and radiologic findings. Although most specimens display nonspecific findings precluding a definitive pathologic diagnosis, pathologists have a unique opportunity to play a crucial role in identifying key histologic features suggestive of certain entities, such as cystic neutrophilic granulomatous mastitis, immunoglobulin (Ig) G4 mastitis, or squamous metaplasia of lactiferous ducts, in the right clinical and radiologic context, and thereby guiding optimal and timely clinical management. The information presented herein will be helpful to practicing anatomic pathologists and pathology trainees in becoming more familiar with specific morphologic features and overcoming differential diagnostic challenges related to pathology reporting of inflammatory lesions of the breast.

Demystifying Breast Disease Markers

Breast imaging radiologists regularly perform image-guided biopsies of suspicious breast lesions based on features that are associated with a likelihood of malignancy ranging from 2% to greater than 95% (Breast Imaging Reporting and Data System categories 4 and 5). As diagnostic partners, pathologists perform histopathologic assessment of these tissue samples to confirm a diagnosis. Correlating the imaging findings with the histopathologic results is an integral aspect of multidisciplinary breast care. Assessment of radiologic-pathologic concordance is vital in guiding appropriate management, as it enables identification of discordant results, minimizing the chance of misdiagnosis. Undersampling can lead to false-negative results, with the frequencies of false-negative diagnoses varying on the basis of multiple factors, including biopsy type (eg, core needle, vacuum-assisted needle), needle gauge, and type of lesion sampled at biopsy (ie, mass, calcifications, asymmetry, architectural distortion). Improving a radiologist's knowledge of macroscopic and microscopic breast anatomy and more common breast diseases and their expected imaging findings ensures more accurate radiologic-pathologic correlation and management recommendations. The histopathologic and molecular characteristics of biopsy-sampled breast lesions aid in making an accurate diagnosis. Hematoxylin-eosin staining provides critical morphologic details, whereas immunohistochemical staining enables molecular characterization of many benign and malignant lesions, which is critical for tailored treatment. The authors review commonly encountered benign and malignant breast diseases, their corresponding histopathologic phenotypes, and the histopathologic markers that are essential to clinching the diagnosis of these entities. As part of a multidisciplinary team that provides optimal patient care, radiologists should be knowledgeable of the foundations of histopathologic diagnosis and the implications for patient management to ensure appropriate radiologic-pathologic concordance. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Idiopathic granulomatous mastitis: a 5-year retrospective review of cases in a tertiary centre in Dublin, Ireland

AIMS

Idiopathic granulomatous mastitis (IGM) is a rare, benign, inflammatory breast disorder of unknown aetiology usually affecting women of reproductive age. It classically presents as a unilateral painful breast mass. It is frequently mistaken for carcinoma or other inflammatory breast diseases. Diagnostic investigations include clinical examination, appropriate imaging and tissue sampling. A link between IGM and infection with the Corynebacterium species in particular Corynebacterium kroppenstedtii has been described.

METHODS

A retrospective single-centre cohort study was conducted over a 5-year period (2017-2022); all cases of IGM were identified.

RESULTS

Forty-one patients were diagnosed with IGM. Breast lump was the most common presenting complaint (n=29). The average age was 45 years. Eighteen patients had samples sent for culture and sensitivity, 11 of which had positive microbiology results indicative of Corynebacterium spp infection.An 82% resolution rate (27 of 33) was recorded in those who received either a short-antibiotic course or none at all. Eight patients reported persistent disease at 3 months, five of which had evidence of Corynebacterium spp.

DISCUSSION

This 5-year review highlights the impact of IGM in a tertiary centre in Dublin, Ireland. Although no treatment guidelines exist, options include antibiotics, immunomodulators and surgery. Due to risk of fistulae and unfavourable cosmetic outcomes, surgery should be reserved for refractory IGM. We suspect that there may be a subset of patients where prolonged antibiotic therapy should be considered. Defining this subgroup requires further study, but likely includes those with cystic neutrophilic granulomatous mastitis, relapsing disease and in whom Corynebacterium spp is recovered.

Cystic neutrophilic granulomatous mastitis: A case report and review of the literature

The present study describes a case of cystic neutrophilic granulomatous mastitis. The clinical and radiological findings of the patient were consistent with idiopathic granulomatous mastitis. Cystic neutrophilic granulomatous mastitis is a rare subtype of mastitis with a distinct histological pattern that is associated with the Corynebacterium species. The diagnosis and treatment of cystic neutrophilic granulomatous mastitis remains a significant challenge due to the scarcity of available data. The present study describes a classic case of cystic neutrophilic granulomatous mastitis that includes clinical, radiological and histopathological findings. To the best of our knowledge, this is the first case documenting radiological findings before and after treatment. This report encourages the consideration of this entity in the differential diagnoses of mastitis.

Granulomatous Mastitis Occurring during Pregnancy: A Case Report

Background and Objectives: Granulomatous mastitis is a benign disease with a clinical presentation similar to that of breast cancer, and is most commonly observed in women of childbearing age. Although it has been suggested that autoimmune diseases are involved in its pathogenesis, no specific treatments have been established. The occurrence of this disease during pregnancy has rarely been reported. We presented the case of a 37-year-old woman who complained of left breast induration at 24 weeks' gestation. Materials and Methods: She was pregnant and manifested a dichorionic, diamniotic placenta. At 24 weeks of gestation, the patient experienced a sensation of hardness in her left breast. Mastitis was suspected, and she was treated with cephem antibiotics. Simultaneously, she was diagnosed with erythema nodosum in the extremities. As her symptoms did not improve, an incisional drainage was performed. Bacterial cultures were obtained at 31 weeks of gestation, and Corynebacterium kroppenstedtii was detected. Results: An elective cesarean section was performed at 37 weeks of gestation, and the baby was delivered safely. After delivery, a needle biopsy was performed, and the patient was diagnosed with granulomatous mastitis. She was completely cured with prednisolone after weaning. In this case, the patient's condition was maintained through incision and drainage, as well as antibiotic, anti-inflammatory, and analgesic drugs during pregnancy. This approach was chosen, taking into consideration the potential side effects of steroids. Conclusions: This case suggests that incisional drainage and antibiotic therapy, as well as steroids and surgery, may be considered in the treatment of granulomatous mastitis occurring during pregnancy. This may also be true for management during delivery. After delivery, breastfeeding and steroidal therapy proved to be effective in treating the condition.

Idiopathic granulomatous mastitis and cystic neutrophilic granulomatous mastitis: two sides of the same coin or distinct entities?

Idiopathic granulomatous mastitis (IGM) is a benign mimic of breast carcinomas. It is defined histologically by the presence of granulomas and inflammation. The closely related cystic neutrophilic granulomatous mastitis (CNGM) shows lipogranulomas, with a reported association with corynebacteria. A large cohort of IGM was reviewed to compare clinical, microbiological and histological features between non-CNGM IGM and CNGM. Cases of IGM were reviewed for histological parameters including the presence of lipogranulomas and composition of inflammatory cells. Clinical data were obtained through hospital records. The cohort included 79 cases, including 51 non-CNGM IGM and 28 CNGM. Comparing non-CNGM IGM and CNGM, there were no differences in clinical or demographical data, other than a younger age of presentation (36.2 vs 41.5 years, p=0.012) for CNGM. Most IGM resolved within the follow-up period (n=57/64, 89.1%), with similar outcomes regardless of treatment (p>0.05). In CNGM, there were more infiltrates of neutrophils (p=0.001), histiocytes (p=0.047), and multinucleated giant cells (p=0.006), but less lymphocytes (p=0.008). Corynebacteria was cultured in two (25%) cases of CNGM, and one non-CNGM IGM (14.3%). Gram-positive bacilli were identified in two cases of CNGM. 'Early' lipogranulomas were observed closely associated to inflamed ducts in three cases of CNGM. Apart from age, there was no distinct clinical or microbiological feature for CNGM. These findings do not support CNGM as a distinct entity. Rather, CNGM-pattern may represent a continuum of IGM, possibly age-related and attributable to ductal inflammation and cystic changes in the breast parenchyma.

Vacuoles in the Breast: A Histologic Clue for an Unusual Presentation of an Atypical Organism

Infections with nontuberculous mycobacteria (NTM) are increasing in prevalence worldwide, and this group of organisms is emerging as significant clinical pathogens. We present a case of a 58-year-old female with persistent furuncles of the breast who was found to have an NTM infection. This case is unique for the lack of risk factors for NTM in the patient's history, the location of the infection in the breast, and the close cooperation needed across disciplines to arrive at the diagnosis. This multi-disciplinary discussion considers the classic clinical presentation of NTM, it is a characteristic morphological appearance on histopathology, the differential diagnosis, treatment, and the ultimate outcome of the case. This case report and discussion will assist both clinicians and pathologists in the diagnosis of this important infectious disease.

Idiopathic Granulomatous Mastitis: Six years of experience and the current evidence in literature

Objectives

This study aimed to retrospectively describe the clinicopathological pattern and management experience of idiopathic granulomatous mastitis in women receiving care at the Royal Hospital, a tertiary care centre in Oman. The study then compared the researchers' experience with the current literature trends.

Methods

The data of patients from January 2012 to December 2017 were reviewed retrospectively, after receiving ethical approval from the Centre of Studies and Research.

Results

This retrospective study included 64 patients were confirmed to have idiopathic granulomatous mastitis. All patients were in the premenopausal phase, with only one being nulliparous. Mastitis was the most common clinical diagnosis; furthermore, half of the patients had a palpable mass. Most patients had received antibiotics during the span of their treatment. Drainage procedure was done in 73% of the patients, whereas excisional procedure was done for 38.7%. Only 52.4% of patients were able to achieve complete clinical resolution within six months of follow-up.

Conclusion

There is no standardised management algorithm due to the paucity of high-level evidence comparing different modalities. However, steroids, methotrexate and surgery are all considered to be effective and acceptable treatments. Moreover, current literature tends towards multimodality treatments planned tailored case-to-case based on the clinical context and patients' preference.

Breast MRI: an illustration of benign findings

Despite its unparalleled sensitivity for aggressive breast cancer, breast MRI continually excites criticism for a specificity that lags behind that of modern mammographic techniques. Radiologists reporting breast MRI need to recognise the range of benign appearances on breast MRI to avoid unnecessary biopsy. This review summarises the reported diagnostic accuracy of breast MRI with particular attention to the technique's specificity, provides a referenced reporting strategy and discusses factors that compromise diagnostic confidence. We then present a pictorial review of benign findings on breast MRI. Enhancing radiological skills to discriminate malignant from benign findings will minimise false positive biopsies, enabling optimal use of multiparametric breast MRI for the benefit of screening clients and breast cancer patients.

Clinical characteristics and microbiota analysis of 44 patients with granulomatous mastitis

Introduction

Granulomatous mastitis (GM) is a chronic inflammatory breast disease. In recent years, the role of Corynebacterium in GM onset has received more and more attention. This study aims to detect the dominant bacterium in GM patients and analyze the association between clinical characteristics and infectious factors.

Methods

In this study, 88 samples from 44 GM patients, six acute lactation mastitis (ALM) patients, and 25 non-inflammatory breast disease (NIB) patients were divided into a GM pus group, a GM tissue group, an ALM pus group, and a NIB tissue group; then, 16S ribosomal DNA sequencing was used to explore their microbiota. The clinical data of all 44 GM patients were also retrospectively collected and analyzed to determine their relationship with infection.

Results

The median age of the 44 GM patients was 33 years, and 88.6% of patients had primary-onset cases, while 11.4% were recurrences; additionally, 89.5% of patients were postpartum and 10.5% were nulliparous. The serum prolactin level was abnormal in nine patients (24.3%). Samples from 15 GM patients (34.1%) had a Corynebacterium abundance of >1% (1.08-80.08%), with eight (53.3%) displaying an abundance of >10%. Corynebacterium was the only genus with significant differences between the GM pus group and the other three groups (p < 0.05). Corynebacterium kroppenstedtii was the predominant Corynebacterium species. Among clinical characteristics, a statistical difference in breast abscess formation was observed according to Corynebacterium abundance in Corynebacterium-positive and- negative patients (p < 0.05).

Discussion

This study explored the relationship between Corynebacterium infection and GM, compared the clinical characteristics between Corynebacterium-positive and- negative patients, and provided support for the role of Corynebacterium species-in particular, C. kroppenstedtii-in the pathogenesis of GM. The detection of Corynebacterium can predict GM onset, especially in patients with high prolactin levels or a history of recent lactation.

Cystic Neutrophilic Granulomatous Mastitis Treatment with Consecutive Dapsone and Adalimumab

Cystic neutrophilic granulomatous mastitis is a rarely reported, benign, mastitis that is not associated with lactation. The pathophysiology is still unknown; however, there is often a relationship with Corynebacterium kroppenstedtii. Cystic neutrophilic mastitis can have deep seated tender nodules and cutaneous ulceration which can clinically resemble pyoderma gangrenous. It can be treatment refractory and can progress to a point where mastectomy is required. This case series reports two patients treated with adalimumab with remission of disease. One patient first received dapsone with remission of symptoms, but incompatible side effects resulted in discontinuation. Both dapsone and adalimumab appear to provide disease remission in patients with cystic neutrophilic granulomatous mastitis.

Further Characterization of Clinicopathologic Features of Cystic Neutrophilic Granulomatous Mastitis

OBJECTIVES

Clinical and demographic features of cystic neutrophilic granulomatous mastitis (CNGM) have not been fully explored due to the rarity of the disease. Herein we studied clinicopathologic characteristics of CNGM in a sizable hospital-based cohort.

METHODS

A case-control study was performed to compare clinicopathologic characteristics between patients with CNGM and granulomatous mastitis other than CNGM and between CNGM with and without Corynebacterium identification.

RESULTS

Cases of CNGM (n = 31) and non-CNGM (n = 30) were included. Compared with the non-CNGM group, patients with CNGM were statistically significantly younger (median age: 38 vs 43 years), were less likely to be smokers (9% vs 40%), were more likely to have a painful lesion (97% vs 77%) or a larger mass-like lesion (median size: 4.6 vs 1.9 cm), and tended to have a higher Breast Imaging Reporting and Data System score in radiologic studies (score ≥4: 81% vs 53%), positive Corynebacterium identification results (36% vs 0%), and a longer resolving time (12 vs 6 months; all P values for above comparisons <.05). Among CNGM cases, patients with and without Corynebacterium identification shared a similar clinicopathologic profile.

CONCLUSIONS

Our study further demonstrated that CNGM is a unique infectious disease with distinct clinicopathologic features.

Clinical features and recurrence of Corynebacterium kroppenstedtii infection in patients with mastitis

Background

Few studies have investigated the differences in clinical features of patients with mastitis following Corynebacterium kroppenstedtii infection, and most focused on the bacterial antimicrobial susceptibility, detection methods and therapy.

Methodology

There were 133 patients with mastitis infected by C. kroppenstedtii between August 2016 and September 2019. C. kroppenstedtii was identified using mass spectrometry. The demographics, clinical diagnosis, laboratory test results of different types of mastitis combined with bacillus infection, and the effects of different treatments in reducing recurrence were compared.

Results

The incidence of pus following C. kroppenstedtii infection was higher in patients with non-granulomatous lobular mastitis (NGLM; 56.6%) than in those with granulomatous lobular mastitis (GLM; 33.3%; χ² = 7.072, p = 0.008). While C-reactive protein (CRP) was higher in the GLM group (12.50 mg/L) than in the NGLM group (6.05 mg/L; Z =  − 2.187, p = 0.029). Treatment with local lavage (triamcinolone acetonide) and antibiotics (cefuroxime) showed a recurrent rate of 25.9% in C. kroppenstedtii infection.

Conclusion

Increased pus, large masses, and an elevated CRP level may occur in patients with mastitis infected by C.kroppenstedtii. These clinical features may guide the determination of the bacterial infection in patients with mastitis. Combining an antibiotic with a triamcinolone acetonide lavage, preferably cefuroxime, may reduce the recurrence.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12905-022-01859-y.

Inflammatory diseases of the breast

Inflammatory disorders of the breast are common benign breast conditions. Lactational mastitis occurs in breastfeeding women and may be associated with breast abscess in severe cases. Non-lactational inflammatory disorders are less common and include idiopathic granulomatous mastitis, periductal mastitis, and tuberculous mastitis. While these disorders have some similarities in their presentation, each disorder requires a specific treatment regimen for resolution, and correct diagnosis is crucial for appropriate treatment. In this chapter, we will review the presentation, diagnosis, and management of each of these distinct clinical entities.

Granulomatous mastitis: An underdiagnosed inflammatory disease afflicting minority women

Granulomatous mastitis (GM) is an underdiagnosed and understudied benign inflammatory disease of the breast whose accurate diagnosis is confounded by mimicry of other breast pathologies (infectious mastitis and abscess, malignancy) and limited clinician knowledge of the disease. GM disproportionately affects minority women, furthering health disparities for a demographic already disadvantaged in the care of breast diseases. The first step in diagnosis is ultrasound followed by core needle biopsy yielding granulomatous inflammation. To far lesser degree, mammography, and MRI may play a role in narrowing the differential. A high index of clinical suspicion and multidisciplinary approach is required. The presence of Corynebacterium kroppensteddti may indicate one subtype of granulomatous mastitis called cystic neutrophilic granulomatous mastitis; disease stratification, and individualized therapy are on the horizon.

Etiology of granulomatous lobular mastitis based on metagenomic next-generation sequencing

OBJECTIVES

We aimed to comprehensively explore the etiology of granulomatous lobular mastitis (GLM) to optimize treatment programs.

METHODS

We collected 30 fresh mastitis samples for metagenomic next-generation sequencing, morphological observation, and analysis of the clinical information.

RESULTS

Of the 30 samples, 25 were GLM; pathogens were detected in 17, these were: Corynebacterium kroppenstedtii (10 of 25, 40%); C. kroppenstedtii and Pseudomonas oleovorans (3 of 25, 12%); C. kroppenstedtii and human gammaherpesvirus 4 (1 of 25, 4%); Acinetobacter baumannii and C. kroppenstedtii (1 of 25, 4%); P. oleovorans (1 of 25, 4%); and Tepidiphilus thermophilus (1 of 25, 4%). Abnormal sex hormone levels (mainly prolactin) and/or autoimmune function were found in 12 of the 25 samples. Lipophilic antibiotics (rifampicin) were found to work effectively in patients with slow-healing wounds after surgery.

CONCLUSIONS

The main pathogenic factor of GLM is C. kroppenstedtii infection, but other unusual pathogens (P. oleovorans, human gammaherpesvirus 4, A. baumannii, T. thermophilus) are likely to be closely related to GLM, particularly human gammaherpesvirus 4 (Epstein-Barr virus)-associated mastitis, which may be a new entity of mastitis. Abnormal levels of sex hormones and autoimmune function are also common causes. Therefore, lipophilic antibiotics (rifampicin) and prolactin inhibitors may be an effective treatment.

Assertive clinical practice in managing patients with idiopathic granulomatous mastitis: Review of literature

Idiopathic granulomatous mastitis (IGM) is a benign persistent inflammatory breast entity characterized histologically by lobulo centric granulomas. Diagnosis may be difficult and involves a strong index of suspicion. There are plentiful studies are published which render the disease more frequently than expected. The strategy for imaging IGM depends on patient age, clinical manifestations, and risk factors. Patients have an excellent prognosis when they are appropriately treated. The management remains contentious, good judgment is required to ensure optimum treatment form and timing.

New Insights of Corynebacterium kroppenstedtii in Granulomatous Lobular Mastitis based on Nanopore Sequencing

BACKGROUND

The etiology of granulomatous lobular mastitis (GLM) remains unknown. This study aimed to detect bacteria in GLM using Nanopore sequencing and identify the relationship between GLM and Corynebacterium kroppenstedtii.

METHODS AND MATERIALS

The bacterial detection on fresh samples (including breast pus and tissue) of 50 GLM patients using nanopore sequencing and culture methods. The bacterial detection rate of participants with different stages were compared and analyzed. Formalin-fixed and paraffin-embedded (FFPE) tissues from 39 patients were performed on Gram staining to identify Gram-positive bacilli (GPB) within lipid vacuoles. Moreover, the clinicopathological characteristics of GLM patients in different bacterial subgroups were also conducted.

RESULTS

In 50 GLM patients, the detection rate of bacteria was 78% using nanopore sequencing method, especially in the early stage of GLM (over 80%), which was significantly higher than that using culture methods (24%, p < 0.001). The dominant bacteria were Corynebacterium species (64%), especially for the Corynebacterium kroppenstedtii. The detection rate of C. kroppenstedtii in nanopore sequencing method (56%) was higher than that in culture methods (16%, p < 0.001). Gram staining positive of bacteria in 7 patients, and 5 of them were C. kroppenstedtii. Thirty-one patients (31/39, 79.5%) exhibited typical histological structure of cystic neutrophilic granulomatous mastitis (CNGM), and eighteen patients detected with C. kroppenstedtii.

CONCLUSION

Nanopore sequencing showed rapid and accurate bacteria detection over culture method in GLM patients. GLM is not sterile inflammation and closely related to C. kroppenstedtii. CNGM was associated with Corynebacterium infection, especially for C. kroppenstedtii.

Granulomatous Mastitis Due to Non-Tuberculous Mycobacteria: A Diagnostic and Therapeutic Dilemma

Non-tuberculous mycobacterial (NTM) infections of the breast are rare. These infections present as cellulitis of the breast or breast abscess. Their diagnosis poses a challenge as they manifest signs of acute inflammation, unlike tuberculous mycobacterial infections which present in a chronic pattern. However, on aspiration of pus from the site of infection, primary smear may show acid fast bacilli. This poses a diagnostic dilemma. The present case is that of a 34-year-old woman who presented with recurrent mastitis. She had history of right breast swelling, for which surgical excision had been performed three months prior at another facility. Her histopathology had showed cystic granulomatous neutrophilic mastitis (CNGM). The patient again presented with right breast abscess which was confirmed on ultrasonography. Incision and drainage along with removal of necrotic tissue was done. Primary smear of pus showed acid fast bacilli on Ziehl-Neelson staining. Bacterial culture and line probe speciation revealed non-tuberculous mycobacterium M. abscessus, which responded well to prolonged anti-microbial therapy. These rapidly growing NTM require prolonged treatment and are quite often recurrent. M. abscessus is a rare cause of CNGM, with this being only the third reported case in literature. A brief case report with a review of literature is presented.

A rheumatologic approach to granulomatous mastitis: A case series and review of the literature

AIM

Idiopathic granulomatous mastitis (IGM) is an enigmatic inflammatory breast disorder. IGM responds to immunomodulatory treatment and may be associated with systemic manifestations such as arthritis and erythema nodosum. These patients are increasingly referred to rheumatologists for management, but IGM is rarely discussed in the rheumatology literature. The objective of this report is to familiarize rheumatologists with the treatment and systemic manifestations of IGM. We report here a case series of IGM at our institution, and a literature review of IGM treated with methotrexate (MTX).

METHOD

Patients with IGM at our institution were identified and described using a retrospective chart review. A literature review of PubMed and Google Scholar identified studies of IGM patients treated with MTX.

RESULTS

We identified 28 IGM patients at our institution. Inflammatory arthritis/arthralgia were present in four patients (14%), and five patients (18%) had erythema nodosum. Patients treated with MTX had the highest rates of relapse-free remission; relapse-free remission occurred in four of the five (80%) MTX-treated patients, compared with 5 of 12 (42%) patients treated with steroids alone, and two or three (66%) patients treated with steroids and surgery. In the literature review, 116 patients treated with MTX were identified, and the rate of relapse-free remission ranged from 58% to 100%. Arthritis/arthralgia and erythema nodosum were more common at our institution than reported in the literature.

CONCLUSION

Methotrexate is a promising treatment for IGM. Arthritis/arthralgias and erythema nodosum may be under-recognized when IGM patients are managed outside rheumatology. Prospective studies are needed to characterize clinical features and optimum treatment of IGM.

Whole genome sequence of Corynebacterium kroppenstedtii isolated from a case of recurrent granulomatous mastitis

We describe the case of a 33-year-old woman with recurrent granulomatous mastitis associated with Corynebacterium kroppenstedtii. This organism has been increasingly associated with granulomatous mastitis, specifically the cystic neutrophilic histopathologic variant, although currently there is a paucity both of reported cases and genomic sequence data. We highlight the challenges in the diagnosis and treatment of this entity, in particular focusing on the various methods of microbiologic identification, including MALDI-TOF, 16 s rRNA PCR and whole-genome sequencing.

Pathology of IgG4-related sclerosing mastitis

Immunoglobulin G4-related sclerosing mastitis (IgG4-RM) is a recently recognised member of the IgG4-related disease (IgG4-RD) family, a multisystem fibroinflammatory condition that can affect any organ system. IgG4-RM is rare and predominantly occurs in middle-aged women. It may present with painless palpable mass and/or lymphadenopathy thereby mimicking breast cancer. Although there is an abundance of literature describing the clinicopathological characteristics of IgG4-RD in a variety of organs, data on IgG4-RM are limited due to its rarity. This review describes the manifestation of the disease in the breast based on reported cases, emphasising the clinicopathological features, pathophysiology, differential diagnosis, treatment and prognosis.

Bacteria Associated with Granulomatous Lobular Mastitis and the Potential for Personalized Therapy

Granulomatous lobular mastitis (GLM), also known as idiopathic granulomatous mastitis (IGM), is a chronic inflammatory lesion of the breast. The incidence of GLM has been increasing in recent years, especially among young women. The etiologies of GLM have not been fully elucidated but are associated with autoimmunity and bacterial infection. Bacteria, especially Corynebacterium species, play important roles in GLM. In this article, we review research progress regarding the bacteriology of GLM attained with the application of several new high-throughput detection techniques. Accurate detection might be important for deepening our understanding of the pathogenesis of GLM and hold promise for personalized GLM therapy.

Cystic neutrophilic granulomatous mastitis during chemotherapy treatment for invasive breast carcinoma – a rare lesion that simulates tumor progression

Background

Cystic neutrophilic granulomatous mastitis (CNGM) is an uncommon and recently described pattern of granulomatous mastitis. To our knowledge, no cases have been described during chemotherapy for invasive breast cancer.

Case presentation

A 42-year-old female patient had a diagnosis of invasive breast carcinoma (3-cm nodule). During neoadjuvant chemotherapy, she presented with an enlargement of the breast nodule that measured 7.0-cm on palpation. The lesion did not show typical inflammatory clinical findings and simulated tumor progression. A core biopsy showed granulomas with pseudocystic spaces with gram-positive bacilli (Corynebacterium sp.), and numerous circumjacent neutrophils. She was treated with antibiotics and resumed chemotherapy. Surgical specimen showed a 1.0-cm residual carcinoma and extensive xanthogranulomatous inflammation with no evidence of residual CNGM.

Conclusion

CNGM is usually associated with typical clinical presentation of mastitis. It is an important pattern of granulomatous inflammation to be recognized in the breast since it directly impacts treatment. The present case highlights its potential occurrence during chemotherapy treatment of breast cancer mimicking progression of breast malignancy.

Cystic neutrophilic granulomatous mastitis - a review of 12 consecutive cases

AIMS

Cystic neutrophilic granulomatous mastitis (CNGM) is an uncommon but increasingly recognised cause of mastitis, often associated with Corynebacterium ssp. infection. We studied the histopathological and clinical features of CNGM in a Canadian setting, and the work-up required to identify pathogenic microorganisms.

METHODS AND RESULTS

A retrospective search for breast specimens with abscess, acute, chronic and/or granulomatous inflammation from 1998 to 2018 was performed. Haematoxylin and eosin slides were reviewed for typical histological features of CNGM. Histochemically stained slides for microorganisms were also reviewed. Repeat Gram stains were performed if initially negative. Electronic medical records were abstracted for microbiology results and relevant clinical data. Twelve cases were identified. All were female, aged 25-57 years, mainly Caucasian, with one Venezuelan and two of Chinese ethnicity. Most were parous (10 of 12); five of 12 had an endocrinopathy. Bacteria were identified in one or more specimens from eight of 12 patients; additional Gram stains revealed organisms in four of 12 cases. Of four bacterial cultures, one grew Corynebacterium kroppenstedtii. 16S polymerase chain reaction for three samples was negative. Two patients had multiple breast biopsies, showing early palisaded granulomas followed by classic features of CNGM. The patients had various management approaches, including surgery and antimicrobials.

CONCLUSIONS

CNGM may present as palisaded granulomatous inflammation, without the expected 'cystic' pattern, suggesting that there is an evolution of histomorphology with this infection. Most patients with CNGM are parous, and there may be an association with endocrinopathies. Application of multiple Gram stains increases the yield of microorganism identification. Recognition of CNGM in breast biopsies and collaborative communications are essential to direct appropriate therapy.