Mastitis, a Radiographic, Clinical, and Histopathologic Review

Research Progress of Plasma Cell Mastitis

BACKGROUND

Plasma cell mastitis (PCM), also termed mammary duct ectasia, is a chronic nonbacterial inflammatory disease characterized by mammary duct dilation and plasma cell infiltration. Due to its varied and nonspecific clinical presentation, PCM is frequently misdiagnosed as breast cancer, complicating clinical management.

OBJECTIVES

This review aims to summarize recent advances in the understanding of PCM, focusing on its etiology, clinical manifestations, diagnosis, and treatment strategies, as well as clarifying differential diagnostic points with granulomatous mastitis (GLM).

METHODS

We reviewed recent literature highlighting clinical characteristics, diagnostic approaches, and therapeutic options related to PCM, including comparative studies addressing differences between PCM and GLM.

DISCUSSION

Recent progress has enhanced understanding of PCM's clinical and pathological features, yet distinguishing PCM from GLM remains clinically challenging due to overlapping presentations. An integrated approach involving clinical evaluation, imaging modalities, and histopathological examination is recommended to improve diagnostic accuracy and clinical outcomes.

CONCLUSION

Further investigation into the pathogenesis of PCM is essential for developing more precise diagnostic criteria and effective treatments, ultimately improving patient prognosis and reducing misdiagnosis.

Treatment of idiopathic granulomatous mastitis: a retrospective case series

Idiopathic granulomatous mastitis (IGM) is a rare inflammatory disease of the breast. Various clinical management approaches have been described, but their efficacy and optimal sequential order remain uncertain. We describe the first Canadian cohort of patients with IGM, discuss treatment outcomes and outline a practical management approach. This retrospective study included patients diagnosed with biopsy-confirmed IGM between 2014 and 2023, aged over 18 years. Based on a scoping review of the literature, a diagnostic and management approach was developed, and we present here the disease course and outcomes using this approach. 22 females were included, with a mean age of 40 (24-65) years, mostly presenting with a breast lump (n =22, 100%) and breast pain (n = 15, 68%). Mean rheumatology follow-up was 28.7 months (range 3-79). Mean time from first symptom to diagnosis was 3.5 months (range 1-13). Corynebacterium kroppenstedtii was found in 8 patients. Treatment including lipophilic antibiotics, corticosteroids and disease modifying anti-rheumatic drugs (DMARDs), led to complete remission in 95% of patients, in a mean time of 11.6 months (range 1-36), and relapse in only 1 patient. 11 patients required DMARDs (50%), most commonly methotrexate (n=9). We highlight the variable severity of IGM and the benefits of a severity-based treatment approach. A diligent evaluation and work-up is essential to manage IGM. The proposed severity-based management approach with medical treatment and less aggressive surgical intervention led to complete remission in 95%.

Diffuse unilateral MRI breast entities

Many benign and malignant breast entities can present with diffuse unilateral magnetic resonance imaging (MRI) findings. The unilateral breast findings can be broken down into three broad categories including asymmetric diffuse masses/non-mass enhancement (NME), diffuse unilateral skin thickening, and diffuse asymmetric background enhancement. Although correlation with clinical history is always necessary, biopsy is often needed to make a definitive diagnosis. There are some findings on MRI which can help narrow the differential including morphology, distribution, T2W signal, enhancement kinetics, and associated skin thickening. Malignant entities which will be discussed in this review include ductal carcinoma in situ, invasive ductal carcinoma, invasive lobular carcinoma, Paget disease, inflammatory breast cancer, and locally advanced breast cancer. Benign entities which will be discussed in this review include idiopathic granulomatous mastitis (IGM), infectious mastitis, pseudoangiomatous stromal hyperplasia, giant fibroadenoma, early and late radiation changes, unilateral breast feeding, and central venous obstruction, all which have varied MRI appearances. It is important for radiologists to be familiar with the common entities that can present with diffuse asymmetric unilateral MRI breast findings to ensure the correct diagnosis and management is undertaken.

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.

An herbal drug combination identified by knowledge graph alleviates the clinical symptoms of plasma cell mastitis patients: A nonrandomized controlled trial

Background

Plasma cell mastitis (PCM) is a nonbacterial breast inflammation with severe and intense clinical manifestation, yet treatment methods for PCM are still rather limited. Although the mechanism of PCM remains unclear, mounting evidence suggests that the dysregulation of immune system is closely associated with the pathogenesis of PCM. Drug combinations or combination therapy could exert improved efficacy and reduced toxicity by hitting multiple discrete cellular targets.

Methods

We have developed a knowledge graph architecture toward immunotherapy and systematic immunity that consists of herbal drug-target interactions with a novel scoring system to select drug combinations based on target-hitting rates and phenotype relativeness. To this end, we employed this knowledge graph to identify an herbal drug combination for PCM and we subsequently evaluated the efficacy of the herbal drug combination in clinical trial.

Results

Our clinical data suggests that the herbal drug combination could significantly reduce the serum level of various inflammatory cytokines, downregulate serum IgA and IgG level, reduce the recurrence rate, and reverse the clinical symptoms of PCM patients with improvements in general health status.

Conclusions

In summary, we reported that an herbal drug combination identified by knowledge graph can alleviate the clinical symptoms of PCM patients. We demonstrated that the herbal drug combination holds great promise as an effective remedy for PCM, acting through the regulation of immunoinflammatory pathways and improvement of systematic immune level. In particular, the herbal drug combination could significantly reduce the recurrence rate of PCM, a major obstacle to PCM treatment. Our data suggests that the herbal drug combination is expected to feature prominently in future PCM treatment.

Funding

C. Liu's lab was supported by grants from the Public Health Science and Technology Project of Shenyang (grant: 22-321-32-18); Y. Yang's laboratory was supported by the National Natural Science Foundation of China (grant: 81874301), the Fundamental Research Funds for Central University (grant: DUT22YG122), and the Key Research project of 'be Recruited and be in Command' in Liaoning Province (2021JH1/10400050).

Clinical trial number

NCT05530226.

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.

Ultrasonic multimodality imaging features and the classification value of nonpuerperal mastitis

OBJECTIVE

To explore the value of ultrasonic multimodality imaging for characterizing nonpuerperal mastitis (NPM) lesions and feasibility of distinguishing different subtypes.

METHODS

Thirty-eight NPM lesions were assessed using conventional ultrasonography (US), strain elastography (SE), and contrast-enhanced ultrasound (CEUS). The lesions were confirmed pathologically and classified as granulomatous lobular mastitis (GLM), plasma cell mastitis (PCM), or nonspecific mastitis (NSM). Furthermore, diagnostic indicators were evaluated. The diagnostic performances of the modalities were compared using the area under the receiver operating characteristic curve (AUC).

RESULTS

The overall morphological features on US differed significantly between the GLM and PCM groups (p = 0.002). Lesion size (≤10 mm) (p = 0.003) and mean SE score (p = 0.001) differed significantly between the PCM and NSM groups. The frequent NPM characteristic on CEUS was hyperenhancement with (or without) increased lesion size; intergroup differences were not significant. Breast Imaging Reporting and Data System > 3 was considered to indicate malignancy; accordingly, the accuracy of US alone, US with CEUS, and US with SE was 10.5%, 21.1%, and 65.8%, respectively. Moreover, the AUC for US with SE for classifying GLM and PCM was 0.616.

CONCLUSION

CEUS cannot accurately classify NPM subtypes, while US and SE are valuable for classification.

Current Understanding and Management of Plasma Cell Mastitis: Can We Benefit from What We Know?

BACKGROUND

Plasma cell mastitis (PCM), also known as mammary duct ectasia, is a chronic nonbacterial breast inflammation characterized by duct expansion and plasma cell infiltration. The severe and intense clinical manifestations profoundly affect the quality of life of female patients. Although the pathological process of PCM is known to include four stages (duct dilatation, inflammation, abscess and fistula), there is still lack of imaging techniques and serum markers with high specificity in clinical practice. Due to recurrent acute attacks and the prolonged healing process of the disease, most patients choose to accept mastectomy.

SUMMARY

We searched for studies, reports and reviews referring to PCM in the past 20 years; more than half of the results were related to animal studies, and little attention has been paid to human beings, which may explain the frequent misdiagnosis of PCM as breast cancer and the limited treatment options. This review focuses on the current diagnostic methods and markers for PCM and hierarchically discusses the typical clinical features, etiological causes and relevant molecular mechanisms of PCM.

KEY MESSAGES

We herein highlight the urgent need to develop more specific and sensitive biomarkers in the clinical laboratory. It will help to establish a standardized flowchart for the diagnosis and treatment of PCM in order to improve recovery for female patients.

Continuous postoperative negative pressure irrigation assisted mammaplasty in treating chronic refractory plasma cell mastitis

Background

Chronic refractory plasma cell mastitis (CRPCM) is an aseptic inflammation of the breast with a chronic course of the disease, extended treatment cycle (months to years), with a high recurrence rate. The objective of this study was to evaluate the efficacy of continuous postoperative negative pressure irrigation assisted mammaplasty (CPNPIAM) in treating CRPCM.

Methods

Between 2016 and 2018, 36 CRPCM patients receiving CPNPIAM were enrolled in this study. CPNPIAM mainly involved complete lesion removal, immediate breast mammaplasty, and continuous postoperative negative pressure irrigation. The age of the patients, local symptoms, history of treatment, the duration of the disease before surgery, hospitalization period, related risk factors, the success rate, the recurrence rate and patients' overall satisfaction ratings were analyzed in the article.

Results

Patients were aged between 22 and 53 years (mean 34.64 years). All patients had a history of conservative treatment or simple drainage. Local symptoms included inflammatory mass (n=36, 100%), abscess (n=33, 92%), nipple discharge (n=7, 19%), inflammatory plaque (n=34, 94%), and sinus tract formation (n=19, 53%). The lesion sizes ranged from 3 to 10 cm (mean 5.13 cm) in diameter. The mean hospitalization period was 8.42 days. The success rate was 100% (36/36) and the recurrence rate was 0% (0/36) at a 3-month follow-up. The patients' overall satisfaction ratings were "very good" (n=22, 61%), "good" (n=12, 33%), and "moderate" (n=2, 6%) with no poor or unsatisfactory ratings.

Conclusions

CPNPIAM is an effective way of treating CRPCM, and showed a high success rate, a low recurrence rate, and high patient satisfaction.

Cystic neutrophilic granulomatous mastitis: The Cleveland Clinic experience with diagnosis and management

Granulomatous mastitis is an uncommon inflammatory disease that typically presents with painful breast lesions. Recent publications have brought to light a specific subset of granulomatous mastitis patients with a distinct histological pattern of disease termed, "cystic neutrophilic granulomatous mastitis" (CNGM). Although many cases of granulomatous lobular mastitis have been thought to be idiopathic, this rare subset of an uncommon disease has been linked to infections with Corynebacterium species. Herein, a cohort of CNGM patients from a large, tertiary care, North-American, academic medical center is presented. Correlative demographic, clinical, radiographic, pathologic, microbiologic, management, and outcomes data are provided. Collaborative communication between specialists to accurately diagnose and manage these patients is essential to decreasing potential morbidity.

Cow-to-mouse fecal transplantations suggest intestinal microbiome as one cause of mastitis

BACKGROUND

Mastitis, which affects nearly all lactating mammals including human, is generally thought to be caused by local infection of the mammary glands. For treatment, antibiotics are commonly prescribed, which however are of concern in both treatment efficacy and neonate safety. Here, using bovine mastitis which is the most costly disease in the dairy industry as a model, we showed that intestinal microbiota alone can lead to mastitis.

RESULTS

Fecal microbiota transplantation (FMT) from mastitis, but not healthy cows, to germ-free (GF) mice resulted in mastitis symptoms in mammary gland and inflammations in serum, spleen, and colon. Probiotic intake in parallel with FMT from diseased cows led to relieved mastitis symptoms in mice, by shifting the murine intestinal microbiota to a state that is functionally distinct from either healthy or diseased microbiota yet structurally similar to the latter. Despite conservation in mastitis symptoms, diseased cows and mice shared few mastitis-associated bacterial organismal or functional markers, suggesting striking divergence in mastitis-associated intestinal microbiota among lactating mammals. Moreover, an "amplification effect" of disease-health distinction in both microbiota structure and function was apparent during the cow-to-mouse FMT.

CONCLUSIONS

Hence, dysbiosis of intestinal microbiota may be one cause of mastitis, and probiotics that restore intestinal microbiota function are an effective and safe strategy to treat mastitis.

Diffusion-weighted imaging in relation to morphology on dynamic contrast enhancement MRI: the diagnostic value of characterizing non-puerperal mastitis

Objectives

To demonstrate the value of diffusion-weighted imaging (DWI) in the characterisation of mastitis lesions.

Methods

Sixty-one non-puerperal patients with pathologically confirmed single benign mastitis lesions underwent preoperative examinations with conventional MRI and axial DWI. Patients were categorised into three groups: (1) periductal mastitis (PDM), (2) granulomatous lobular mastitis (GLM), and (3) infectious abscess (IAB). Apparent diffusion coefficient (ADC) values of each lesion were recorded. A one-way ANOVA with logistic analysis was performed to compare ADC values and other parameters. Discriminative abilities of DWI modalities were compared using the area under the receiver operating characteristic curve (AUC). P < 0.05 was considered statistically significant.

Results

ADC values differed significantly among the three groups (P = 0.003) as well as between PDM and IAB and between PDM and GLM. The distribution of non-mass enhancement on dynamic contrast-enhanced (DCE) MRI differed significantly among the three groups (P = 0.03) but not between any two groups specifically. There were no differences in lesion location, patient age, T₂WI or DWI signal intensity, enhancement type, non-mass internal enhancement, or mass enhancement characteristics among the three groups.

Conclusions

ADC values and the distribution of non-mass enhancement are valuable in classifying mastitis subtypes.

Key points

• Mastitis subtypes exhibit different characteristics on DWI and DCE MRI.

• ADC values are helpful in isolating PDM from other mastitis lesions.

• Distribution of non-mass enhancement also has value in comparing mastitis subtypes.

Idiopathic Granulomatous Mastitis: Cytologic and Histologic Study of 65 Egyptian Patients

BACKGROUND

The etiology of idiopathic granulomatous mastitis (IGM) is unknown, and it is commonly misdiagnosed clinically and/or radiologically as breast cancer. The role of fine-needle aspiration cytology (FNAC) in its diagnosis is still a matter of debate. The aim of the current study is to assess the value of FNAC in the diagnosis of IGM, and to search for the presence of bacteria in IGM with cystic vacuoles, which was described recently by a few authors.

MATERIALS AND METHODS

Retrospective study of cytologic smears and histologic tissue sections of 65 Egyptian IGM cases was done along with microbiologic testing. A comparison of the frequency of IGM in Egypt to that of other populations was also made.

RESULTS

IGM has typical FNA features which can easily exclude malignancy. Histologically, cystic vacuoles were encountered in 35 out of 65 cases (53.9%), with only 6 (17.14%) of these cases showing Gram-positive bacilli (GPB). The frequency of IGM in Egypt is comparable to those in other Middle Eastern countries but much higher than in Western countries.

CONCLUSION

IGM is a common breast disease in Egypt. FNAC in IGM has a high diagnostic accuracy. This study supports the few recent studies that have detected GPB in IGM with cystic vacuoles. Thus, bacteriologic examination in such cases may affect the treatment strategy.

Imaging features of idiopathic granulomatous mastitis - Case report

Idiopathic granulomatous mastitis is a rare disorder of unknown etiology. This disease occurs mostly in young women and often after the lactation period. Women usually present with a fixed, painful mass, sparing the retroareolar region, associated with skin thickening and possible ulceration that mimics carcinoma. Nipple discharge can be present and bilateral involvement may occur in up to 25% of cases. In this case report, we present a typical case of histologically confirmed idiopathic granulomatous mastitis, highlighting the imaging findings, including magnetic resonance imaging (MRI), which may favor this diagnosis and enable better clinical management of these patients.